4-piperidin-n-(pyrimidin-4-yl)chroman-7-sulfonamide derivatives as sodium channel inhibitors

ABSTRACT

The invention provides 4-piperidin-chroman-7-sulfonamide derivatives and salts thereof that are sodium channel modulators, as well as compositions containing such a compound or salt and therapeutic methods for using such a compound, salt, or composition.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a 35 U.S.C. § 371 application of International Application No. PCT/US2018/023740, filed Mar. 22, 2018, and claims priority to international patent application number PCT/CN2017/078017, filed Mar. 24, 2017. The entire content of international patent application number PCT/CN2017/078017 is hereby incorporated by reference herein.

BACKGROUND

The present invention relates to organic compounds useful for therapy in a mammal, and in particular to inhibitors of sodium channel (e.g., NaV1.7) that are useful for treating sodium channel-mediated diseases or conditions, such as pain, as well as other diseases and conditions associated with the modulation of sodium channels.

Voltage-gated sodium channels are transmembrane proteins that initiate action potentials in nerve, muscle and other electrically excitable cells, and are a necessary component of normal sensation, emotions, thoughts and movements (Catterall, W. A., Nature (2001), Vol. 409, pp. 988-990). These channels consist of a highly processed alpha subunit that is associated with auxiliary beta subunits. The pore-forming alpha subunit is sufficient for channel function, but the kinetics and voltage dependence of channel gating are in part modified by the beta subunits (Goldin et al., Neuron (2000), Vol. 28, pp. 365-368). Electrophysiological recording, biochemical purification, and molecular cloning have identified ten different sodium channel alpha subunits and four beta subunits (Yu, F. H., et al., Sci. STKE (2004), 253; and Yu, F. H., et al., Neurosci. (2003), 20:7577-85).

The sodium channel family of proteins has been extensively studied and shown to be involved in a number of vital body functions. Research in this area has identified variants of the alpha subunits that result in major changes in channel function and activities, which can ultimately lead to major pathophysiological conditions. The members of this family of proteins are denoted NaV1.1 to NaV1.9.

NaV1.7 is a tetrodotoxin-sensitive voltage-gated sodium channel encoded by the gene SCN9A. Human NaV1.7 was first cloned from neuroendocrine cells (Klugbauer, N., et al., 1995 EMBO J., 14 (6): 1084-90) and rat NaV1.7 was cloned from a pheochromocytoma PC12 cell line (Toledo-Aral, J. J., et al., Proc. Natl. Acad. Sci. USA (1997), 94:1527-1532) and from rat dorsal root ganglia (Sangameswaran, L., et al., (1997), J. Biol. Chem., 272 (23): 14805-9). NaV1.7 is expressed primarily in the peripheral nervous system, especially nocieptors and olfactory neurons and sympathetic neurons. The inhibition, or blocking, of NaV1.7 has been shown to result in analgesic activity. Knockout of NaV1.7 expression in a subset of sensory neurons that are predominantly nociceptive results in resistance to inflammatory pain (Nassar, et al., op. cit.). Likewise, loss of function mutations in humans results in congenital indifference to pain (CIP), in which the individuals are resistant to both inflammatory and neuropathic pain (Cox, J. J., et al., Nature (2006); 444:894-898; Goldberg, Y. P., et al., Clin. Genet. (2007); 71:311-319). Conversely, gain of function mutations in NaV1.7 have been established in two human heritable pain conditions, primary erythromelalgia and familial rectal pain, (Yang, Y., et al., J. Med. Genet. (2004), 41(3):171-4). In addition, a single nucleotide polymorphism (R1150W) that has very subtle effects on the time- and voltage-dependence of channel gating has large effects on pain perception (Estacion, M., et al., 2009. Ann Neurol 66: 862-6; Reimann, F., et al., Proc Natl Acad Sci USA (2010), 107: 5148-53). About 10% of the patients with a variety of pain conditions have the allele conferring greater sensitivity to pain and thus might be more likely to respond to block of NaV1.7. Because NaV1.7 is expressed in both sensory and sympathetic neurons, one might expect that enhanced pain perception would be accompanied by cardiovascular abnormalities such as hypertension, but no correlation has been reported. Thus, both the CIP mutations and SNP analysis suggest that human pain responses are more sensitive to changes in NaV1.7 currents than are perturbations of autonomic function.

Sodium channel blockers have been shown to be useful in the treatment of pain, (see, e.g., Wood, J. N., et al., J. Neurobiol. (2004), 61(1), 55-71. Genetic and functional studies have provided evidence to support that activity of NaV1.7 as a major contributor to pain signalling in mammals. (See Hajj, et al. Nature Reviews Neuroscience; 2013, vol 14, 49-62; and Lee, et al. Cell; 2014, vol 157; 1-12). Presently, there are a limited number of effective sodium channel blockers for the treatment of pain with a minimum of adverse side effects which are currently in the clinic. Thus there remains a need for selective voltage-gated sodium channel modulators (e.g., modulators of NaV1.7) that can provide a greater therapeutic index for treatment. There is also a need for selective voltage-gated sodium channel modulators that have potent in vivo activity and that have good metabolic stability.

SUMMARY OF THE INVENTION

In one aspect the present invention provides novel compounds having sodium channel blocking activity that are useful for the treatment of pain. Certain compounds of the invention have potent in vivo activity and good metabolic stability.

In a first embodiment, the invention provides a compound of formula I that is selected from the group consisting of:

-   (S)-6-fluoro-4-((2S,4R)-2-(pyridin-2-yl)-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide; -   (S)-6-fluoro-4-((2S,4S)-2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide; -   (S)-4-((2S,4R)-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidin-1-yl)-6-fluoro-N-(pyrimidin-4-yl)chroman-7-sulfonamide;     and -   (S)-6-fluoro-4-((2R,4R)-2-methyl-4-(3-(trifluoromethyl)phenyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide;     or a pharmaceutically acceptable thereof.

In another aspect the present invention provides for a pharmaceutical composition comprising a compound of formula I or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient.

In another aspect the present invention provides a method of treating a disease or condition in a mammal selected from the group consisting of pain, depression, cardiovascular diseases, respiratory diseases, and psychiatric diseases, and combinations thereof, comprising administering to the mammal a therapeutically effective amount of a compound of formula I or a pharmaceutically acceptable salt thereof. In another aspect of the present invention said disease or condition is selected from the group consisting of neuropathic pain, inflammatory pain, visceral pain, cancer pain, chemotherapy pain, trauma pain, surgical pain, post-surgical pain, childbirth pain, labor pain, neurogenic bladder, ulcerative colitis, chronic pain, persistent pain, peripherally mediated pain, centrally mediated pain, chronic headache, migraine headache, sinus headache, tension headache, phantom limb pain, dental pain, peripheral nerve injury or a combination thereof. In another aspect of the present invention said disease or condition is selected from the group consisting of pain associated with HIV, HIV treatment induced neuropathy, trigeminal neuralgia, post-herpetic neuralgia, eudynia, heat sensitivity, tosarcoidosis, irritable bowel syndrome, Crohns disease, pain associated with multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), diabetic neuropathy, peripheral neuropathy, arthritis, rheumatoid arthritis, osteoarthritis, atherosclerosis, paroxysmal dystonia, myasthenia syndromes, myotonia, malignant hyperthermia, cystic fibrosis, pseudoaldosteronism, rhabdomyolysis, hypothyroidism, bipolar depression, anxiety, schizophrenia, sodium channel toxin related illnesses, familial erythromelalgia, primary erythromelalgia, familial rectal pain, cancer, epilepsy, partial and general tonic seizures, restless leg syndrome, arrhythmias, fibromyalgia, neuroprotection under ischaemic conditions cause by stroke or neural trauma, tach-arrhythmias, atrial fibrillation and ventricular fibrillation.

In another aspect the present invention provides for a method of treating pain in a mammal by the inhibition of ion flux through a voltage-dependent sodium channel in the mammal, wherein the method comprises administering to the mammal a therapeutically effective amount of a compound of formula I or a pharmaceutically acceptable salt thereof.

In another aspect the present invention provides for a method of decreasing ion flux through a voltage-dependent sodium channel in a cell in a mammal, wherein the method comprises contacting the cell with a compound of formula I or a pharmaceutically acceptable salt thereof.

In another aspect the present invention provides for a method of treating pruritus in a mammal, wherein the method comprises administering to the mammal a therapeutically effective amount of a compound of formula I or a pharmaceutically acceptable salt thereof.

In another aspect the present invention provides for a method of treating cancer in a mammal, wherein the method comprises administering to the mammal a therapeutically effective amount a compound of formula I or a pharmaceutically acceptable salt thereof.

In another aspect the present invention provides for a method of treating, but not preventing, pain in a mammal, wherein the method comprises administering to the mammal a therapeutically effective amount of a compound of formula I or a pharmaceutically acceptable salt thereof. In another aspect of the present invention the pain is selected from the group consisting of neuropathic pain, inflammatory pain, visceral pain, cancer pain, chemotherapy pain, trauma pain, surgical pain, post-surgical pain, childbirth pain, labor pain, neurogenic bladder, ulcerative colitis, chronic pain, persistent pain, peripherally mediated pain, centrally mediated pain, chronic headache, migraine headache, sinus headache, tension headache, phantom limb pain, dental pain, peripheral nerve injury or a combination thereof. In another aspect the present invention the pain is associated with a disease or condition selected from the group consisting of HIV, HIV treatment induced neuropathy, trigeminal neuralgia, post-herpetic neuralgia, eudynia, heat sensitivity, tosarcoidosis, irritable bowel syndrome, Crohns disease, pain associated with multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), diabetic neuropathy, peripheral neuropathy, arthritis, rheumatoid arthritis, osteoarthritis, atherosclerosis, paroxysmal dystonia, myasthenia syndromes, myotonia, malignant hyperthermia, cystic fibrosis, pseudoaldosteronism, rhabdomyolysis, hypothyroidism, bipolar depression, anxiety, schizophrenia, sodium channel toxin related illnesses, familial erythromelalgia, primary erythromelalgia, familial rectal pain, cancer, epilepsy, partial and general tonic seizures, restless leg syndrome, arrhythmias, fibromyalgia, neuroprotection under ischaemic conditions cause by stroke or neural trauma, tach-arrhythmias, atrial fibrillation and ventricular fibrillation.

In another aspect the present invention provides for a method for the treatment or prophylaxis of pain, depression, cardiovascular disease, respiratory disease, or psychiatric disease, or a combinations thereof, in an animal which method comprises administering an effective amount of a compound of formula I, or a pharmaceutically acceptable salt thereof.

In another aspect the present invention provides for a compound of formula I, or a pharmaceutically acceptable salt thereof for the use as a medicament for the treatment of diseases and disorders selected from the group consisting of pain, depression, cardiovascular diseases, respiratory diseases, and psychiatric diseases, or a combination thereof.

In another aspect the present invention provides for the use of a compound of formula I, or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment of diseases and disorders selected from the group consisting of pain, depression, cardiovascular diseases, respiratory diseases, and psychiatric diseases, or a combination thereof.

In another aspect the present invention provides for the invention as described herein.

DETAILED DESCRIPTION OF THE INVENTION Definitions

As used herein, the term “chiral” refers to molecules which have the property of non-superimposability of the mirror image partner, while the term “achiral” refers to molecules which are superimposable on their mirror image partner.

As used herein, the term “stereoisomers” refers to compounds which have identical chemical constitution, but differ with regard to the arrangement of the atoms or groups in space.

As used herein a wavy line “

” that intersects a bond in a chemical structure indicates the point of attachment of the bond that the wavy bond intersects in the chemical structure to the remainder of a molecule.

“Diastereomer” refers to a stereoisomer with two or more centers of chirality and whose molecules are not mirror images of one another. Diastereomers have different physical properties, e.g. melting points, boiling points, spectral properties, and reactivities. Mixtures of diastereomers can separate under high resolution analytical procedures such as electrophoresis and chromatography.

“Enantiomers” refer to two stereoisomers of a compound which are non-superimposable mirror images of one another.

Stereochemical definitions and conventions used herein generally follow S. P. Parker, Ed., McGraw-Hill Dictionary of Chemical Terms (1984) McGraw-Hill Book Company, New York; and Eliel, E. and Wilen, S., “Stereochemistry of Organic Compounds”, John Wiley & Sons, Inc., New York, 1994. The compounds of the invention can contain asymmetric or chiral centers, and therefore exist in different stereoisomeric forms. It is intended that all stereoisomeric forms of the compounds of the invention, including but not limited to, diastereomers, enantiomers and atropisomers, as well as mixtures thereof such as racemic mixtures, form part of the present invention. Many organic compounds exist in optically active forms, i.e., they have the ability to rotate the plane of plane-polarized light. In describing an optically active compound, the prefixes D and L, or R and S, are used to denote the absolute configuration of the molecule about its chiral center(s). The prefixes d and 1 or (+) and (−) are employed to designate the sign of rotation of plane-polarized light by the compound, with (−) or 1 meaning that the compound is levorotatory. A compound prefixed with (+) or d is dextrorotatory. For a given chemical structure, these stereoisomers are identical except that they are mirror images of one another. A specific stereoisomer can also be referred to as an enantiomer, and a mixture of such isomers is often called an enantiomeric mixture. A 50:50 mixture of enantiomers is referred to as a racemic mixture or a racemate, which can occur where there has been no stereoselection or stereospecificity in a chemical reaction or process. The terms “racemic mixture” and “racemate” refer to an equimolar mixture of two enantiomeric species, devoid of optical activity.

When a bond in a compound formula herein is drawn in a non-stereochemical manner (e.g. flat), the atom to which the bond is attached includes all stereochemical possibilities. When a bond in a compound formula herein is drawn in a defined stereochemical manner (e.g. bold, bold-wedge, dashed or dashed-wedge), it is to be understood that the atom to which the stereochemical bond is attached is enriched in the absolute stereoisomer depicted unless otherwise noted. In one embodiment, the compound may be at least 51% the absolute stereoisomer depicted. In another embodiment, the compound may be at least 80% the absolute stereoisomer depicted. In another embodiment, the compound may be at least 90% the absolute stereoisomer depicted. In another embodiment, the compound may be at least 95% the absolute stereoisomer depicted. In another embodiment, the compound may be at least 97% the absolute stereoisomer depicted. In another embodiment, the compound may be at least 98% the absolute stereoisomer depicted. In another embodiment, the compound may be at least 99% the absolute stereoisomer depicted.

As used herein, the term “tautomer” or “tautomeric form” refers to structural isomers of different energies which are interconvertible via a low energy barrier. For example, proton tautomers (also known as prototropic tautomers) include interconversions via migration of a proton, such as keto-enol and imine-enamine isomerizations. Valence tautomers include interconversions by reorganization of some of the bonding electrons.

As used herein, the term “solvate” refers to an association or complex of one or more solvent molecules and a compound of the invention. Examples of solvents that form solvates include, but are not limited to, water, isopropanol, ethanol, methanol, DMSO, ethyl acetate, acetic acid, and ethanolamine. The term “hydrate” refers to the complex where the solvent molecule is water.

As used herein, the term “protecting group” refers to a substituent that is commonly employed to block or protect a particular functional group on a compound. For example, an “amino-protecting group” is a substituent attached to an amino group that blocks or protects the amino functionality in the compound. Suitable amino-protecting groups include acetyl, trifluoroacetyl, t-butoxycarbonyl (BOC), benzyloxycarbonyl (CBZ) and 9-fluorenylmethylenoxycarbonyl (Fmoc). Similarly, a “hydroxy-protecting group” refers to a substituent of a hydroxy group that blocks or protects the hydroxy functionality. Suitable protecting groups include acetyl and silyl. A “carboxy-protecting group” refers to a substituent of the carboxy group that blocks or protects the carboxy functionality. Common carboxy-protecting groups include phenylsulfonylethyl, cyanoethyl, 2-(trimethylsilyl)ethyl, 2-(trimethylsilyl)ethoxymethyl, 2-(p-toluenesulfonyl)ethyl, 2-(p-nitrophenylsulfenyl)ethyl, 2-(diphenylphosphino)-ethyl, nitroethyl and the like. For a general description of protecting groups and their use, see P. G. M. Wuts and T. W. Greene, Greene's Protective Groups in Organic Synthesis 4^(th) edition, Wiley-Interscience, New York, 2006.

As used herein, the term “mammal” includes, but is not limited to, humans, mice, rats, guinea pigs, monkeys, dogs, cats, horses, cows, pigs, and sheep.

As used herein, the term “pharmaceutically acceptable salts” is meant to include salts of the active compounds which are prepared with relatively nontoxic acids or bases, depending on the particular substituents found on the compounds described herein. When compounds of the present invention contain relatively acidic functionalities, base addition salts can be obtained by contacting the neutral form of such compounds with a sufficient amount of the desired base, either neat or in a suitable inert solvent. Examples of salts derived from pharmaceutically-acceptable inorganic bases include aluminum, ammonium, calcium, copper, ferric, ferrous, lithium, magnesium, manganic, manganous, potassium, sodium, zinc and the like. Salts derived from pharmaceutically-acceptable organic bases include salts of primary, secondary and tertiary amines, including substituted amines, cyclic amines, naturally-occurring amines and the like, such as arginine, betaine, caffeine, choline, N,N′-dibenzylethylenediamine, diethylamine, 2-diethylaminoethanol, 2-dimethylaminoethanol, ethanolamine, ethylenediamine, N-ethylmorpholine, N-ethylpiperidine, glucamine, glucosamine, histidine, hydrabamine, isopropylamine, lysine, methylglucamine, morpholine, piperazine, piperidine, polyamine resins, procaine, purines, theobromine, triethylamine, trimethylamine, tripropylamine, tromethamine and the like. When compounds of the present invention contain relatively basic functionalities, acid addition salts can be obtained by contacting the neutral form of such compounds with a sufficient amount of the desired acid, either neat or in a suitable inert solvent. Examples of pharmaceutically acceptable acid addition salts include those derived from inorganic acids like hydrochloric, hydrobromic, nitric, carbonic, monohydrogencarbonic, phosphoric, monohydrogenphosphoric, dihydrogenphosphoric, sulfuric, monohydrogensulfuric, hydriodic, or phosphorous acids and the like, as well as the salts derived from relatively nontoxic organic acids like acetic, propionic, isobutyric, malonic, benzoic, succinic, suberic, fumaric, mandelic, phthalic, benzenesulfonic, p-tolylsulfonic, citric, tartaric, methanesulfonic, and the like. Also included are salts of amino acids such as arginate and the like, and salts of organic acids like glucuronic or galactunoric acids and the like (see, for example, Berge, S. M., et al., “Pharmaceutical Salts”, Journal of Pharmaceutical Science, 1977, 66, 1-19). Certain specific compounds of the present invention contain both basic and acidic functionalities that allow the compounds to be converted into either base or acid addition salts.

The neutral forms of the compounds can be regenerated by contacting the salt with a base or acid and isolating the parent compound in the conventional manner. The parent form of the compound differs from the various salt forms in certain physical properties, such as solubility in polar solvents, but otherwise the salts are equivalent to the parent form of the compound for the purposes of the present invention.

In addition to salt forms, the present invention provides compounds which are in a prodrug form. As used herein the term “prodrug” refers to those compounds that readily undergo chemical changes under physiological conditions to provide the compounds of the present invention. Additionally, prodrugs can be converted to the compounds of the present invention by chemical or biochemical methods in an ex vivo environment. For example, prodrugs can be slowly converted to the compounds of the present invention when placed in a transdermal patch reservoir with a suitable enzyme or chemical reagent.

Prodrugs of the invention include compounds wherein an amino acid residue, or a polypeptide chain of two or more (e.g., two, three or four) amino acid residues, is covalently joined through an amide or ester bond to a free amino, hydroxy or carboxylic acid group of a compound of the present invention. The amino acid residues include but are not limited to the 20 naturally occurring amino acids commonly designated by three letter symbols and also includes phosphoserine, phosphothreonine, phosphotyrosine, 4-hydroxyproline, hydroxylysine, demosine, isodemosine, gamma-carboxyglutamate, hippuric acid, octahydroindole-2-carboxylic acid, statine, 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid, penicillamine, ornithine, 3-methylhistidine, norvaline, beta-alanine, gamma-aminobutyric acid, citrulline, homocysteine, homoserine, methyl-alanine, para-benzoylphenylalanine, phenylglycine, propargylglycine, sarcosine, methionine sulfone and tert-butylglycine.

Additional types of prodrugs are also encompassed. For instance, a free carboxyl group of a compound of the invention can be derivatized as an amide or alkyl ester. As another example, compounds of this invention comprising free hydroxy groups can be derivatized as prodrugs by converting the hydroxy group into a group such as, but not limited to, a phosphate ester, hemisuccinate, dimethylaminoacetate, or phosphoryloxymethyloxycarbonyl group, as outlined in Fleisher, D. et al., (1996) Improved oral drug delivery: solubility limitations overcome by the use of prodrugs Advanced Drug Delivery Reviews, 19:115. Carbamate prodrugs of hydroxy and amino groups are also included, as are carbonate prodrugs, sulfonate esters and sulfate esters of hydroxy groups. Derivatization of hydroxy groups as (acyloxy)methyl and (acyloxy)ethyl ethers, wherein the acyl group can be an alkyl ester optionally substituted with groups including, but not limited to, ether, amine and carboxylic acid functionalities, or where the acyl group is an amino acid ester as described above, are also encompassed. Prodrugs of this type are described in J. Med. Chem., (1996), 39:10. More specific examples include replacement of the hydrogen atom of the alcohol group with a group such as (C₁₋₆)alkanoyloxymethyl, 1-((C₁₋₆)alkanoyloxy)ethyl, 1-methyl-1-((C₁₋₆)alkanoyloxy)ethyl, (C₁₋₆)alkoxycarbonyloxymethyl, N—(C₁₋₆)alkoxycarbonylaminomethyl, succinoyl, (C₁₋₆)alkanoyl, alpha-amino(C₁₋₄)alkanoyl, arylacyl and alpha-aminoacyl, or alpha-aminoacyl-alpha-aminoacyl, where each alpha-aminoacyl group is independently selected from the naturally occurring L-amino acids, P(O)(OH)₂, —P(O)(O(C₁₋₆)alkyl)₂ or glycosyl (the radical resulting from the removal of a hydroxyl group of the hemiacetal form of a carbohydrate).

For additional examples of prodrug derivatives, see, for example, a) Design of Prodrugs, edited by H. Bundgaard, (Elsevier, 1985) and Methods in Enzymology, Vol. 42, p. 309-396, edited by K. Widder, et al. (Academic Press, 1985); b) A Textbook of Drug Design and Development, edited by Krogsgaard-Larsen and H. Bundgaard, Chapter 5 “Design and Application of Prodrugs,” by H. Bundgaard p. 113-191 (1991); c) H. Bundgaard, Advanced Drug Delivery Reviews, 8:1-38 (1992); d) H. Bundgaard, et al., Journal of Pharmaceutical Sciences, 77:285 (1988); and e) N. Kakeya, et al., Chem. Pharm. Bull., 32:692 (1984), each of which is specifically incorporated herein by reference.

Additionally, the present invention provides for metabolites of compounds of the invention. As used herein, a “metabolite” refers to a product produced through metabolism in the body of a specified compound or salt thereof. Such products can result for example from the oxidation, reduction, hydrolysis, amidation, deamidation, esterification, deesterification, enzymatic cleavage, and the like, of the administered compound.

Metabolite products typically are identified by preparing a radiolabelled (e.g., ¹⁴C or ³H) isotope of a compound of the invention, administering it parenterally in a detectable dose (e.g., greater than about 0.5 mg/kg) to an animal such as rat, mouse, guinea pig, monkey, or to man, allowing sufficient time for metabolism to occur (typically about 30 seconds to 30 hours) and isolating its conversion products from the urine, blood or other biological samples. These products are easily isolated since they are labeled (others are isolated by the use of antibodies capable of binding epitopes surviving in the metabolite). The metabolite structures are determined in conventional fashion, e.g., by MS, LC/MS or NMR analysis. In general, analysis of metabolites is done in the same way as conventional drug metabolism studies well known to those skilled in the art. The metabolite products, so long as they are not otherwise found in vivo, are useful in diagnostic assays for therapeutic dosing of the compounds of the invention.

Certain compounds of the present invention can exist in unsolvated forms as well as solvated forms, including hydrated forms. In general, the solvated forms are equivalent to unsolvated forms and are intended to be encompassed within the scope of the present invention. Certain compounds of the present invention can exist in multiple crystalline or amorphous forms. In general, all physical forms are equivalent for the uses contemplated by the present invention and are intended to be within the scope of the present invention.

Certain compounds of the present invention possess asymmetric carbon atoms (optical centers) or double bonds; the racemates, diastereomers, geometric isomers, regioisomers and individual isomers (e.g., separate enantiomers) are all intended to be encompassed within the scope of the present invention.

The terms “treat” and “treatment” refer to both therapeutic treatment and/or prophylactic treatment or preventative measures, wherein the object is to prevent or slow down (lessen) an undesired physiological change or disorder, such as, for example, the development or spread of cancer. For purposes of this invention, beneficial or desired clinical results include, but are not limited to, alleviation of symptoms, diminishment of extent of disease or disorder, stabilized (i.e., not worsening) state of disease or disorder, delay or slowing of disease progression, amelioration or palliation of the disease state or disorder, and remission (whether partial or total), whether detectable or undetectable. “Treatment” can also mean prolonging survival as compared to expected survival if not receiving treatment. Those in need of treatment include those already with the disease or disorder as well as those prone to have the disease or disorder or those in which the disease or disorder is to be prevented.

The phrase “therapeutically effective amount” or “effective amount” means an amount of a compound of the present invention that (i) treats or prevents the particular disease, condition, or disorder, (ii) attenuates, ameliorates, or eliminates one or more symptoms of the particular disease, condition, or disorder, or (iii) prevents or delays the onset of one or more symptoms of the particular disease, condition, or disorder described herein. For cancer therapy, efficacy can, for example, be measured by assessing the time to disease progression (TTP) and/or determining the response rate (RR).

Compounds

In one aspect the present invention provides the following compounds as described herein:

-   (S)-6-fluoro-4-((2S,4R)-2-(pyridin-2-yl)-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide; -   (S)-6-fluoro-4-((2S,4S)-2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide; -   (S)-4-((2S,4R)-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidin-1-yl)-6-fluoro-N-(pyrimidin-4-yl)chroman-7-sulfonamide;     and -   (S)-6-fluoro-4-((2R,4R)-2-methyl-4-(3-(trifluoromethyl)phenyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide;     or a pharmaceutically acceptable thereof.

Compounds of provided herein may be prepared by any feasible synthetic route known to one of ordinary skill in the art, for example, by the process illustrated in Scheme 1 below.

Pharmaceutical Compositions and Administration

In addition to one or more of the compounds provided above (or stereoisomers, geometric isomers, tautomers, solvates, metabolites, isotopes, pharmaceutically acceptable salts, or prodrugs thereof), the invention also provides for compositions and medicaments comprising a compound of formula I or and embodiment thereof and at least one pharmaceutically acceptable carrier, diluent or excipient. The compositions of the invention can be used to selectively inhibit NaV1.7 in patients (e.g, humans).

The term “composition,” as used herein, is intended to encompass a product comprising the specified ingredients in the specified amounts, as well as any product which results, directly or indirectly, from combination of the specified ingredients in the specified amounts. By “pharmaceutically acceptable” it is meant the carrier, diluent or excipient must be compatible with the other ingredients of the formulation and not deleterious to the recipient thereof.

In one embodiment, the invention provides for pharmaceutical compositions (or medicaments) comprising a compound of formula I or an embodiment thereof, and its stereoisomers, geometric isomers, tautomers, solvates, metabolites, isotopes, pharmaceutically acceptable salts, or prodrugs thereof) and a pharmaceutically acceptable carrier, diluent or excipient. In another embodiment, the invention provides for preparing compositions (or medicaments) comprising compounds of the invention. In another embodiment, the invention provides for administering compounds of formula I or its embodiments and compositions comprising compounds of formula I or an embodiment thereof to a patient (e.g., a human patient) in need thereof.

Compositions are formulated, dosed, and administered in a fashion consistent with good medical practice. Factors for consideration in this context include the particular disorder being treated, the particular mammal being treated, the clinical condition of the individual patient, the cause of the disorder, the site of delivery of the agent, the method of administration, the scheduling of administration, and other factors known to medical practitioners. The effective amount of the compound to be administered will be governed by such considerations, and is the minimum amount necessary to inhibit NaV1.7 activity as required to prevent or treat the undesired disease or disorder, such as for example, pain. For example, such amount may be below the amount that is toxic to normal cells, or the mammal as a whole.

In one example, the therapeutically effective amount of the compound of the invention administered parenterally per dose will be in the range of about 0.01-100 mg/kg, alternatively about e.g., 0.1 to 20 mg/kg of patient body weight per day, with the typical initial range of compound used being 0.3 to 15 mg/kg/day. The daily does is, in certain embodiments, given as a single daily dose or in divided doses two to six times a day, or in sustained release form. In the case of a 70 kg adult human, the total daily dose will generally be from about 7 mg to about 1,400 mg. This dosage regimen may be adjusted to provide the optimal therapeutic response. The compounds may be administered on a regimen of 1 to 4 times per day, preferably once or twice per day.

The compounds of the present invention may be administered in any convenient administrative form, e.g., tablets, powders, capsules, solutions, dispersions, suspensions, syrups, sprays, suppositories, gels, emulsions, patches, etc. Such compositions may contain components conventional in pharmaceutical preparations, e.g., diluents, carriers, pH modifiers, sweeteners, bulking agents, and further active agents.

The compounds of the invention may be administered by any suitable means, including oral, topical (including buccal and sublingual), rectal, vaginal, transdermal, parenteral, subcutaneous, intraperitoneal, intrapulmonary, intradermal, intrathecal and epidural and intranasal, and, if desired for local treatment, intralesional administration. Parenteral infusions include intramuscular, intravenous, intraarterial, intraperitoneal, intracerebral, intraocular, intralesional or subcutaneous administration.

The compositions comprising compounds of formula I or an embodiment thereof are normally formulated in accordance with standard pharmaceutical practice as a pharmaceutical composition. A typical formulation is prepared by mixing a compound of the present invention and a diluent, carrier or excipient. Suitable diluents, carriers and excipients are well known to those skilled in the art and are described in detail in, e.g., Ansel, Howard C., et al., Ansel's Pharmaceutical Dosage Forms and Drug Delivery Systems. Philadelphia: Lippincott, Williams & Wilkins, 2004; Gennaro, Alfonso R., et al. Remington: The Science and Practice of Pharmacy. Philadelphia: Lippincott, Williams & Wilkins, 2000; and Rowe, Raymond C. Handbook of Pharmaceutical Excipients. Chicago, Pharmaceutical Press, 2005. The formulations may also include one or more buffers, stabilizing agents, surfactants, wetting agents, lubricating agents, emulsifiers, suspending agents, preservatives, antioxidants, opaquing agents, glidants, processing aids, colorants, sweeteners, perfuming agents, flavoring agents, diluents and other known additives to provide an elegant presentation of the drug (i.e., a compound of the present invention or pharmaceutical composition thereof) or aid in the manufacturing of the pharmaceutical product (i.e., medicament).

Suitable carriers, diluents and excipients are well known to those skilled in the art and include materials such as carbohydrates, waxes, water soluble and/or swellable polymers, hydrophilic or hydrophobic materials, gelatin, oils, solvents, water and the like. The particular carrier, diluent or excipient used will depend upon the means and purpose for which a compound of the present invention is being applied. Solvents are generally selected based on solvents recognized by persons skilled in the art as safe (GRAS) to be administered to a mammal. In general, safe solvents are non-toxic aqueous solvents such as water and other non-toxic solvents that are soluble or miscible in water. Suitable aqueous solvents include water, ethanol, propylene glycol, polyethylene glycols (e.g., PEG 400, PEG 300), etc. and mixtures thereof. The formulations can also include one or more buffers, stabilizing agents, surfactants, wetting agents, lubricating agents, emulsifiers, suspending agents, preservatives, antioxidants, opaquing agents, glidants, processing aids, colorants, sweeteners, perfuming agents, flavoring agents and other known additives to provide an elegant presentation of the drug (i.e., a compound of the present invention or pharmaceutical composition thereof) or aid in the manufacturing of the pharmaceutical product (i.e., medicament).

Acceptable diluents, carriers, excipients and stabilizers are nontoxic to recipients at the dosages and concentrations employed, and include buffers such as phosphate, citrate and other organic acids; antioxidants including ascorbic acid and methionine; preservatives (such as octadecyldimethylbenzyl ammonium chloride; hexamethonium chloride; benzalkonium chloride, benzethonium chloride; phenol, butyl or benzyl alcohol; alkyl parabens such as methyl or propyl paraben; catechol; resorcinol; cyclohexanol; 3-pentanol; and m-cresol); low molecular weight (less than about 10 residues) polypeptides; proteins, such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, histidine, arginine, or lysine; monosaccharides, disaccharides and other carbohydrates including glucose, mannose, or dextrins; chelating agents such as EDTA; sugars such as sucrose, mannitol, trehalose or sorbitol; salt-forming counter-ions such as sodium; metal complexes (e.g., Zn-protein complexes); and/or non-ionic surfactants such as TWEEN™, PLURONICS™ or polyethylene glycol (PEG). A active pharmaceutical ingredient of the invention (e.g., compound of formula I or an embodiment thereof) can also be entrapped in microcapsules prepared, for example, by coacervation techniques or by interfacial polymerization, for example, hydroxymethylcellulose or gelatin-microcapsules and poly-(methylmethacylate) microcapsules, respectively, in colloidal drug delivery systems (for example, liposomes, albumin microspheres, microemulsions, nano-particles and nanocapsules) or in macroemulsions. Such techniques are disclosed in Remington: The Science and Practice of Pharmacy: Remington the Science and Practice of Pharmacy (2005) 21^(st) Edition, Lippincott Williams & Wilkins, Philidelphia, Pa.

Sustained-release preparations of a compound of the invention (e.g., compound of formula I or an embodiment thereof) can be prepared. Suitable examples of sustained-release preparations include semipermeable matrices of solid hydrophobic polymers containing a compound of formula I or an embodiment thereof, which matrices are in the form of shaped articles, e.g., films, or microcapsules. Examples of sustained-release matrices include polyesters, hydrogels (for example, poly(2-hydroxyethyl-methacrylate), or poly(vinyl alcohol)), polylactides (U.S. Pat. No. 3,773,919), copolymers of L-glutamic acid and gamma-ethyl-L-glutamate (Sidman et al., Biopolymers 22:547, 1983), non-degradable ethylene-vinyl acetate (Langer et al., J. Biomed. Mater. Res. 15:167, 1981), degradable lactic acid-glycolic acid copolymers such as the LUPRON DEPOT™ (injectable microspheres composed of lactic acid-glycolic acid copolymer and leuprolide acetate) and poly-D-(−)-3-hydroxybutyric acid (EP 133,988A). Sustained release compositions also include liposomally entrapped compounds, which can be prepared by methods known per se (Epstein et al., Proc. Natl. Acad. Sci. U.S.A. 82:3688, 1985; Hwang et al., Proc. Natl. Acad. Sci. U.S.A. 77:4030, 1980; U.S. Pat. Nos. 4,485,045 and 4,544,545; and EP 102,324A). Ordinarily, the liposomes are of the small (about 200-800 Angstroms) unilamelar type in which the lipid content is greater than about 30 mol % cholesterol, the selected proportion being adjusted for the optimal therapy.

The formulations include those suitable for the administration routes detailed herein. The formulations can conveniently be presented in unit dosage form and can be prepared by any of the methods well known in the art of pharmacy. Techniques and formulations generally are found in Remington: The Science and Practice of Pharmacy: Remington the Science and Practice of Pharmacy (2005) 21^(st) Edition, Lippincott Williams & Wilkins, Philidelphia, Pa. Such methods include the step of bringing into association the active ingredient with the carrier which constitutes one or more accessory ingredients.

In general the formulations are prepared by uniformly and intimately bringing into association the active ingredient with liquid carriers, diluents or excipients or finely divided solid carriers, diluents or excipients, or both, and then, if necessary, shaping the product. A typical formulation is prepared by mixing a compound of the present invention and a carrier, diluent or excipient. The formulations can be prepared using conventional dissolution and mixing procedures. For example, the bulk drug substance (i.e., compound of the present invention or stabilized form of the compound (e.g., complex with a cyclodextrin derivative or other known complexation agent) is dissolved in a suitable solvent in the presence of one or more of the excipients described above. A compound of the present invention is typically formulated into pharmaceutical dosage forms to provide an easily controllable dosage of the drug and to enable patient compliance with the prescribed regimen.

In one example, compounds of formula I or an embodiment thereof may be formulated by mixing at ambient temperature at the appropriate pH, and at the desired degree of purity, with physiologically acceptable carriers, i.e., carriers that are non-toxic to recipients at the dosages and concentrations employed into a galenical administration form. The pH of the formulation depends mainly on the particular use and the concentration of compound, but preferably ranges anywhere from about 3 to about 8. In one example, a compound of formula I (or an embodiment thereof) is formulated in an acetate buffer, at pH 5. In another embodiment, the compounds of formula I or an embodiment thereof are sterile. The compound may be stored, for example, as a solid or amorphous composition, as a lyophilized formulation or as an aqueous solution.

Formulations of a compound of the invention (e.g., compound of formula I or an embodiment thereof) suitable for oral administration can be prepared as discrete units such as pills, capsules, cachets or tablets each containing a predetermined amount of a compound of the invention.

Compressed tablets can be prepared by compressing in a suitable machine the active ingredient in a free-flowing form such as a powder or granules, optionally mixed with a binder, lubricant, inert diluent, preservative, surface active or dispersing agent. Molded tablets can be made by molding in a suitable machine a mixture of the powdered active ingredient moistened with an inert liquid diluent. The tablets can optionally be coated or scored and optionally are formulated so as to provide slow or controlled release of the active ingredient therefrom.

Tablets, troches, lozenges, aqueous or oil suspensions, dispersible powders or granules, emulsions, hard or soft capsules, e.g., gelatin capsules, syrups or elixirs can be prepared for oral use. Formulations of a compound of the invention (e.g., compound of formula I or an embodiment thereof) intended for oral use can be prepared according to any method known to the art for the manufacture of pharmaceutical compositions and such compositions can contain one or more agents including sweetening agents, flavoring agents, coloring agents and preserving agents, in order to provide a palatable preparation. Tablets containing the active ingredient in admixture with non-toxic pharmaceutically acceptable excipient which are suitable for manufacture of tablets are acceptable. These excipients can be, for example, inert diluents, such as calcium or sodium carbonate, lactose, calcium or sodium phosphate; granulating and disintegrating agents, such as maize starch, or alginic acid; binding agents, such as starch, gelatin or acacia; and lubricating agents, such as magnesium stearate, stearic acid or talc. Tablets can be uncoated or can be coated by known techniques including microencapsulation to delay disintegration and adsorption in the gastrointestinal tract and thereby provide a sustained action over a longer period. For example, a time delay material such as glyceryl monostearate or glyceryl distearate alone or with a wax can be employed.

An example of a suitable oral administration form is a tablet containing about 1 mg, 5 mg, 10 mg, 25 mg, 30 mg, 50 mg, 80 mg, 100 mg, 150 mg, 250 mg, 300 mg and 500 mg of the compound of the invention compounded with about 90-30 mg anhydrous lactose, about 5-40 mg sodium croscarmellose, about 5-30 mg polyvinylpyrrolidone (PVP) K30, and about 1-10 mg magnesium stearate. The powdered ingredients are first mixed together and then mixed with a solution of the PVP. The resulting composition can be dried, granulated, mixed with the magnesium stearate and compressed to tablet form using conventional equipment. An example of an aerosol formulation can be prepared by dissolving the compound, for example 5-400 mg, of the invention in a suitable buffer solution, e.g. a phosphate buffer, adding a tonicifier, e.g. a salt such sodium chloride, if desired. The solution may be filtered, e.g., using a 0.2 micron filter, to remove impurities and contaminants.

For treatment of the eye or other external tissues, e.g., mouth and skin, the formulations are preferably applied as a topical ointment or cream containing the active ingredient(s) in an amount of, for example, 0.075 to 20% w/w. When formulated in an ointment, the active ingredient can be employed with either a paraffinic or a water-miscible ointment base. Alternatively, the active ingredients can be formulated in a cream with an oil-in-water cream base. If desired, the aqueous phase of the cream base can include a polyhydric alcohol, i.e., an alcohol having two or more hydroxyl groups such as propylene glycol, butane 1,3-diol, mannitol, sorbitol, glycerol and polyethylene glycol (including PEG 400) and mixtures thereof. The topical formulations can desirably include a compound which enhances absorption or penetration of the active ingredient through the skin or other affected areas. Examples of such dermal penetration enhancers include dimethyl sulfoxide and related analogs.

The oily phase of the emulsions of this invention can be constituted from known ingredients in a known manner. While the phase can comprise merely an emulsifier, it desirably comprises a mixture of at least one emulsifier with a fat or an oil or with both a fat and an oil. Preferably, a hydrophilic emulsifier is included together with a lipophilic emulsifier which acts as a stabilizer. It is also preferred to include both an oil and a fat. Together, the emulsifier(s) with or without stabilizer(s) make up the so-called emulsifying wax, and the wax together with the oil and fat make up the so-called emulsifying ointment base which forms the oily dispersed phase of the cream formulations. Emulsifiers and emulsion stabilizers suitable for use in the formulation of the invention include Tween® 60, Span® 80, cetostearyl alcohol, benzyl alcohol, myristyl alcohol, glyceryl mono-stearate and sodium lauryl sulfate.

In one aspect of topical applications, it is desired to administer an effective amount of a pharmaceutical composition according to the invention to target area, e.g., skin surfaces, mucous membranes, and the like, which are adjacent to peripheral neurons which are to be treated. This amount will generally range from about 0.0001 mg to about 1 g of a compound of the invention per application, depending upon the area to be treated, whether the use is diagnostic, prophylactic or therapeutic, the severity of the symptoms, and the nature of the topical vehicle employed. A preferred topical preparation is an ointment, wherein about 0.001 to about 50 mg of active ingredient is used per cc of ointment base. The pharmaceutical composition can be formulated as transdermal compositions or transdermal delivery devices (“patches”). Such compositions include, for example, a backing, active compound reservoir, a control membrane, liner and contact adhesive. Such transdermal patches may be used to provide continuous pulsatile, or on demand delivery of the compounds of the present invention as desired.

Aqueous suspensions of a compound of the invention (e.g., compound of formula I or an embodiment thereof) contain the active materials in admixture with excipients suitable for the manufacture of aqueous suspensions. Such excipients include a suspending agent, such as sodium carboxymethylcellulose, croscarmellose, povidone, methylcellulose, hydroxypropyl methylcellulose, sodium alginate, polyvinylpyrrolidone, gum tragacanth and gum acacia, and dispersing or wetting agents such as a naturally occurring phosphatide (e.g., lecithin), a condensation product of an alkylene oxide with a fatty acid (e.g., polyoxyethylene stearate), a condensation product of ethylene oxide with a long chain aliphatic alcohol (e.g., heptadecaethyleneoxycetanol), a condensation product of ethylene oxide with a partial ester derived from a fatty acid and a hexitol anhydride (e.g., polyoxyethylene sorbitan monooleate). The aqueous suspension can also contain one or more preservatives such as ethyl or n-propyl p-hydroxybenzoate, one or more coloring agents, one or more flavoring agents and one or more sweetening agents, such as sucrose or saccharin.

Formulations of a compound of the invention (e.g., compound of formula I or an embodiment thereof) can be in the form of a sterile injectable preparation, such as a sterile injectable aqueous or oleaginous suspension. This suspension can be formulated according to the known art using those suitable dispersing or wetting agents and suspending agents which have been mentioned above. The sterile injectable preparation can also be a sterile injectable solution or suspension in a non-toxic parenterally acceptable diluent or solvent, such as a solution in 1,3-butanediol or prepared as a lyophilized powder. Among the acceptable vehicles and solvents that can be employed are water, Ringer's solution and isotonic sodium chloride solution. In addition, sterile fixed oils can conventionally be employed as a solvent or suspending medium. For this purpose any bland fixed oil can be employed including synthetic mono- or diglycerides. In addition, fatty acids such as oleic acid can likewise be used in the preparation of injectables.

The amount of active ingredient that can be combined with the carrier material to produce a single dosage form will vary depending upon the host treated and the particular mode of administration. For example, a time-release formulation intended for oral administration to humans can contain approximately 1 to 1000 mg of active material compounded with an appropriate and convenient amount of carrier material which can vary from about 5 to about 95% of the total compositions (weight:weight). The pharmaceutical composition can be prepared to provide easily measurable amounts for administration. For example, an aqueous solution intended for intravenous infusion can contain from about 3 to 500 μg of the active ingredient per milliliter of solution in order that infusion of a suitable volume at a rate of about 30 mL/hr can occur.

Formulations suitable for parenteral administration include aqueous and non-aqueous sterile injection solutions which can contain anti-oxidants, buffers, bacteriostats and solutes which render the formulation isotonic with the blood of the intended recipient; and aqueous and non-aqueous sterile suspensions which can include suspending agents and thickening agents.

Formulations suitable for topical administration to the eye also include eye drops wherein the active ingredient is dissolved or suspended in a suitable carrier, especially an aqueous solvent for the active ingredient. The active ingredient is preferably present in such formulations in a concentration of about 0.5 to 20% w/w, for example about 0.5 to 10% w/w, for example about 1.5% w/w.

Formulations suitable for topical administration in the mouth include lozenges comprising the active ingredient in a flavored basis, usually sucrose and acacia or tragacanth; pastilles comprising the active ingredient in an inert basis such as gelatin and glycerin, or sucrose and acacia; and mouthwashes comprising the active ingredient in a suitable liquid carrier.

Formulations for rectal administration can be presented as a suppository with a suitable base comprising for example cocoa butter or a salicylate.

Formulations suitable for intrapulmonary or nasal administration have a particle size for example in the range of 0.1 to 500 microns (including particle sizes in a range between 0.1 and 500 microns in increments microns such as 0.5, 1, 30 microns, 35 microns, etc.), which is administered by rapid inhalation through the nasal passage or by inhalation through the mouth so as to reach the alveolar sacs. Suitable formulations include aqueous or oily solutions of the active ingredient. Formulations suitable for aerosol or dry powder administration can be prepared according to conventional methods and can be delivered with other therapeutic agents such as compounds heretofore used in the treatment of disorders as described below.

The formulations can be packaged in unit-dose or multi-dose containers, for example sealed ampoules and vials, and can be stored in a freeze-dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example water, for injection immediately prior to use. Extemporaneous injection solutions and suspensions are prepared from sterile powders, granules and tablets of the kind previously described. Preferred unit dosage formulations are those containing a daily dose or unit daily sub-dose, as herein above recited, or an appropriate fraction thereof, of the active ingredient.

When the binding target is located in the brain, certain embodiments of the invention provide for a compound of formula I (or an embodiment thereof) to traverse the blood-brain barrier. Certain neurodegenerative diseases are associated with an increase in permeability of the blood-brain barrier, such that a compound of formula I (or an embodiment thereof) can be readily introduced to the brain. When the blood-brain barrier remains intact, several art-known approaches exist for transporting molecules across it, including, but not limited to, physical methods, lipid-based methods, and receptor and channel-based methods.

Physical methods of transporting a compound of formula I (or an embodiment thereof) across the blood-brain barrier include, but are not limited to, circumventing the blood-brain barrier entirely, or by creating openings in the blood-brain barrier.

Circumvention methods include, but are not limited to, direct injection into the brain (see, e.g., Papanastassiou et al., Gene Therapy 9:398-406, 2002), interstitial infusion/convection-enhanced delivery (see, e.g., Bobo et al., Proc. Natl. Acad. Sci. U.S.A. 91:2076-2080, 1994), and implanting a delivery device in the brain (see, e.g., Gill et al., Nature Med. 9:589-595, 2003; and Gliadel Wafers™, Guildford Pharmaceutical). Methods of creating openings in the barrier include, but are not limited to, ultrasound (see, e.g., U.S. Patent Publication No. 2002/0038086), osmotic pressure (e.g., by administration of hypertonic mannitol (Neuwelt, E. A., Implication of the Blood-Brain Barrier and its Manipulation, Volumes 1 and 2, Plenum Press, N.Y., 1989)), and permeabilization by, e.g., bradykinin or permeabilizer A-7 (see, e.g., U.S. Pat. Nos. 5,112,596, 5,268,164, 5,506,206, and 5,686,416).

Lipid-based methods of transporting a compound of formula I (or an embodiment thereof) across the blood-brain barrier include, but are not limited to, encapsulating the a compound of formula I (or an embodiment thereof) in liposomes that are coupled to antibody binding fragments that bind to receptors on the vascular endothelium of the blood-brain barrier (see, e.g., U.S. Patent Application Publication No. 2002/0025313), and coating a compound of formula I (or an embodiment thereof) in low-density lipoprotein particles (see, e.g., U.S. Patent Application Publication No. 2004/0204354) or apolipoprotein E (see, e.g., U.S. Patent Application Publication No. 2004/0131692).

Receptor and channel-based methods of transporting a compound of formula I (or an embodiment thereof) across the blood-brain barrier include, but are not limited to, using glucocorticoid blockers to increase permeability of the blood-brain barrier (see, e.g., U.S. Patent Application Publication Nos. 2002/0065259, 2003/0162695, and 2005/0124533); activating potassium channels (see, e.g., U.S. Patent Application Publication No. 2005/0089473), inhibiting ABC drug transporters (see, e.g., U.S. Patent Application Publication No. 2003/0073713); coating a compound of formula I (or an embodiment thereof) with a transferrin and modulating activity of the one or more transferrin receptors (see, e.g., U.S. Patent Application Publication No. 2003/0129186), and cationizing the antibodies (see, e.g., U.S. Pat. No. 5,004,697).

For intracerebral use, in certain embodiments, the compounds can be administered continuously by infusion into the fluid reservoirs of the CNS, although bolus injection may be acceptable. The inhibitors can be administered into the ventricles of the brain or otherwise introduced into the CNS or spinal fluid. Administration can be performed by use of an indwelling catheter and a continuous administration means such as a pump, or it can be administered by implantation, e.g., intracerebral implantation of a sustained-release vehicle. More specifically, the inhibitors can be injected through chronically implanted cannulas or chronically infused with the help of osmotic minipumps. Subcutaneous pumps are available that deliver proteins through a small tubing to the cerebral ventricles. Highly sophisticated pumps can be refilled through the skin and their delivery rate can be set without surgical intervention. Examples of suitable administration protocols and delivery systems involving a subcutaneous pump device or continuous intracerebroventricular infusion through a totally implanted drug delivery system are those used for the administration of dopamine, dopamine agonists, and cholinergic agonists to Alzheimer's disease patients and animal models for Parkinson's disease, as described by Harbaugh, J. Neural Transm. Suppl. 24:271, 1987; and DeYebenes et al., Mov. Disord. 2: 143, 1987.

A compound of formula I (or an embodiment thereof) used in the invention are formulated, dosed, and administered in a fashion consistent with good medical practice. Factors for consideration in this context include the particular disorder being treated, the particular mammal being treated, the clinical condition of the individual patient, the cause of the disorder, the site of delivery of the agent, the method of administration, the scheduling of administration, and other factors known to medical practitioners. A compound of formula I (or an embodiment thereof) need not be, but is optionally formulated with one or more agent currently used to prevent or treat the disorder in question. The effective amount of such other agents depends on the amount of a compound of the invention present in the formulation, the type of disorder or treatment, and other factors discussed above.

These are generally used in the same dosages and with administration routes as described herein, or about from 1 to 99% of the dosages described herein, or in any dosage and by any route that is empirically/clinically determined to be appropriate.

For the prevention or treatment of disease, the appropriate dosage of a compound of formula I (or an embodiment thereof) (when used alone or in combination with other agents) will depend on the type of disease to be treated, the properties of the compound, the severity and course of the disease, whether the compound is administered for preventive or therapeutic purposes, previous therapy, the patient's clinical history and response to the compound, and the discretion of the attending physician. The compound is suitably administered to the patient at one time or over a series of treatments. Depending on the type and severity of the disease, about 1 μg/kg to 15 mg/kg (e.g., 0.1 mg/kg-10 mg/kg) of compound can be an initial candidate dosage for administration to the patient, whether, for example, by one or more separate administrations, or by continuous infusion. One typical daily dosage might range from about 1 μg kg to 100 mg/kg or more, depending on the factors mentioned above. For repeated administrations over several days or longer, depending on the condition, the treatment would generally be sustained until a desired suppression of disease symptoms occurs. One exemplary dosage of a compound of formula I (or an embodiment thereof) would be in the range from about 0.05 mg/kg to about 10 mg/kg. Thus, one or more doses of about 0.5 mg/kg, 2.0 mg/kg, 4.0 mg/kg, or 10 mg/kg (or any combination thereof) may be administered to the patient. Such doses may be administered intermittently, e.g., every week or every three weeks (e.g., such that the patient receives from about two to about twenty, or, e.g., about six doses of the antibody). An initial higher loading dose, followed by one or more lower doses may be administered. An exemplary dosing regimen comprises administering an initial loading dose of about 4 mg/kg, followed by a weekly maintenance dose of about 2 mg kg of the compound. However, other dosage regimens may be useful. The progress of this therapy is easily monitored by conventional techniques and assays.

Other typical daily dosages might range from, for example, about 1 g/kg to up to 100 mg/kg or more (e.g., about 1 μg kg to 1 mg/kg, about 1 μg/kg to about 5 mg/kg, about 1 mg kg to 10 mg/kg, about 5 mg/kg to about 200 mg/kg, about 50 mg/kg to about 150 mg/mg, about 100 mg/kg to about 500 mg/kg, about 100 mg/kg to about 400 mg/kg, and about 200 mg/kg to about 400 mg/kg), depending on the factors mentioned above. Typically, the clinician will administer a compound until a dosage is reached that results in improvement in or, optimally, elimination of, one or more symptoms of the treated disease or condition. The progress of this therapy is easily monitored by conventional assays. One or more agent provided herein may be administered together or at different times (e.g., one agent is administered prior to the administration of a second agent). One or more agent may be administered to a subject using different techniques (e.g., one agent may be administered orally, while a second agent is administered via intramuscular injection or intranasally). One or more agent may be administered such that the one or more agent has a pharmacologic effect in a subject at the same time. Alternatively, one or more agent may be administered, such that the pharmacological activity of the first administered agent is expired prior the administration of one or more secondarily administered agents (e.g., 1, 2, 3, or 4 secondarily administered agents).

Indications and Methods of Treatment

The compounds of the invention modulate, preferably inhibit, ion flux through a voltage-dependent sodium channel in a mammal, (e.g, a human). Any such modulation, whether it be partial or complete inhibition or prevention of ion flux, is sometimes referred to herein as “blocking” and corresponding compounds as “blockers” or “inhibitors”. In general, the compounds of the invention modulate the activity of a sodium channel downwards by inhibiting the voltage-dependent activity of the sodium channel, and/or reduce or prevent sodium ion flux across a cell membrane by preventing sodium channel activity such as ion flux.

Accordingly, the compounds of the invention are sodium channel blockers and are therefore useful for treating diseases and conditions in mammals, for example humans, and other organisms, including all those diseases and conditions which are the result of aberrant voltage-dependent sodium channel biological activity or which may be ameliorated by modulation of voltage-dependent sodium channel biological activity. In particular, the compounds of the invention, i.e., the compounds of formula (I) and embodiments and (or stereoisomers, geometric isomers, tautomers, solvates, metabolites, isotopes, pharmaceutically acceptable salts, or prodrugs thereof), are useful for treating diseases and conditions in mammals, for example humans, which are the result of aberrant voltage-dependent NaV1.7 biological activity or which may be ameliorated by the modulation, preferably the inhibition, of NaV1.7 biological activity. In certain aspects, the compounds of the invention selectively inhibit NaV1.7 over NaV1.5.

As defined herein, a sodium channel-mediated disease or condition refers to a disease or condition in a mammal, preferably a human, which is ameliorated upon modulation of the sodium channel and includes, but is not limited to, pain, central nervous conditions such as epilepsy, anxiety, depression and bipolar disease; cardiovascular conditions such as arrhythmias, atrial fibrillation and ventricular fibrillation; neuromuscular conditions such as restless leg syndrome and muscle paralysis or tetanus; neuroprotection against stroke, neural trauma and multiple sclerosis; and channelopathies such as erythromyalgia and familial rectal pain syndrome.

In one aspect, the present invention relates to compounds, pharmaceutical compositions and methods of using the compounds and pharmaceutical compositions for the treatment of sodium channel-mediated diseases in mammals, preferably humans and preferably diseases and conditions related to pain, central nervous conditions such as epilepsy, anxiety, depression and bipolar disease; cardiovascular conditions such as arrhythmias, atrial fibrillation and ventricular fibrillation; neuromuscular conditions such as restless leg syndrome and muscle paralysis or tetanus; neuroprotection against stroke, neural trauma and multiple sclerosis; and channelopathies such as erythromyalgia and familial rectal pain syndrome, by administering to a mammal, for example a human, in need of such treatment an effective amount of a sodium channel blocker modulating, especially inhibiting, agent.

A sodium channel-mediated disease or condition also includes pain associated with HIV, HIV treatment induced neuropathy, trigeminal neuralgia, glossopharyngeal neuralgia, neuropathy secondary to metastatic infiltration, adiposis dolorosa, thalamic lesions, hypertension, autoimmune disease, asthma, drug addiction (e.g., opiate, benzodiazepine, amphetamine, cocaine, alcohol, butane inhalation), Alzheimer, dementia, age-related memory impairment, Korsakoff syndrome, restenosis, urinary dysfunction, incontinence, Parkinson's disease, cerebrovascular ischemia, neurosis, gastrointestinal disease, sickle cell anemia, transplant rejection, heart failure, myocardial infarction, reperfusion injury, intermittant claudication, angina, convulsion, respiratory disorders, cerebral or myocardial ischemias, long-QT syndrome, Catecholeminergic polymorphic ventricular tachycardia, ophthalmic diseases, spasticity, spastic paraplegia, myopathies, myasthenia gravis, paramyotonia congentia, hyperkalemic periodic paralysis, hypokalemic periodic paralysis, alopecia, anxiety disorders, psychotic disorders, mania, paranoia, seasonal affective disorder, panic disorder, obsessive compulsive disorder (OCD), phobias, autism, Aspergers Syndrome, Retts syndrome, disintegrative disorder, attention deficit disorder, aggressivity, impulse control disorders, thrombosis, pre clampsia, congestive cardiac failure, cardiac arrest, Freidrich's ataxia, Spinocerebellear ataxia, myelopathy, radiculopathy, systemic lupus erythamatosis, granulomatous disease, olivo-ponto-cerebellar atrophy, spinocerebellar ataxia, episodic ataxia, myokymia, progressive pallidal atrophy, progressive supranuclear palsy and spasticity, traumatic brain injury, cerebral oedema, hydrocephalus injury, spinal cord injury, anorexia nervosa, bulimia, Prader-Willi syndrome, obesity, optic neuritis, cataract, retinal haemorrhage, ischaemic retinopathy, retinitis pigmentosa, acute and chronic glaucoma, macular degeneration, retinal artery occlusion, Chorea, Huntington's chorea, cerebral edema, proctitis, post-herpetic neuralgia, eudynia, heat sensitivity, sarcoidosis, irritable bowel syndrome, Tourette syndrome, Lesch-Nyhan Syndrome, Brugado syndrome, Liddle syndrome, Crohns disease, multiple sclerosis and the pain associated with multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), disseminated sclerosis, diabetic neuropathy, peripheral neuropathy, charcot marie tooth syndrome, arthritic, rheumatoid arthritis, osteoarthritis, chondrocalcinosis, atherosclerosis, paroxysmal dystonia, myasthenia syndromes, myotonia, myotonic dystrophy, muscular dystrophy, malignant hyperthermia, cystic fibrosis, pseudoaldosteronism, rhabdomyolysis, mental handicap, hypothyroidism, bipolar depression, anxiety, schizophrenia, sodium channel toxin related illnesses, familial erythromelalgia, primary erythromelalgia, rectal pain, cancer, epilepsy, partial and general tonic seizures, febrile seizures, absence seizures (petit mal), myoclonic seizures, atonic seizures, clonic seizures, Lennox Gastaut, West Syndome (infantile spasms), multiresistant seizures, seizure prophylaxis (anti-epileptogenic), familial Mediterranean fever syndrome, gout, restless leg syndrome, arrhythmias, fibromyalgia, neuroprotection under ischaemic conditions caused by stroke or neural trauma, tachy-arrhythmias, atrial fibrillation and ventricular fibrillation and as a general or local anaesthetic.

As used herein, the term “pain” refers to all categories of pain and is recognized to include, but is not limited to, neuropathic pain, inflammatory pain, nociceptive pain, idiopathic pain, neuralgic pain, orofacial pain, burn pain, burning mouth syndrome, somatic pain, visceral pain, myofacial pain, dental pain, cancer pain, chemotherapy pain, trauma pain, surgical pain, post-surgical pain, childbirth pain, labor pain, chronic regional pain syndrome (CRPS), reflex sympathetic dystrophy, brachial plexus avulsion, neurogenic bladder, acute pain (e.g., musculoskeletal and post-operative pain), chronic pain, persistent pain, peripherally mediated pain, centrally mediated pain, chronic headache, migraine headache, familial hemiplegic migraine, conditions associated with cephalic pain, sinus headache, tension headache, phantom limb pain, peripheral nerve injury, pain following stroke, thalamic lesions, radiculopathy, HIV pain, post-herpetic pain, non-cardiac chest pain, irritable bowel syndrome and pain associated with bowel disorders and dyspepsia, and combinations thereof.

Furthermore, sodium channel blockers have clinical uses in addition to pain. The present invention therefore also relates to compounds, pharmaceutical compositions and methods of using the compounds and pharmaceutical compositions for the treatment of diseases or conditions such as cancer and pruritus (itch).

Pruritus, commonly known as itch, is a common dermatological condition. While the exact causes of pruritus are complex and incompletely understood, there has long been evidence that itch involves sensory neurons, especially C fibers, similar to those that mediate pain (Schmelz, M., et al., J. Neurosci. (1997), 17: 8003-8). In particular, it is believed that sodium influx through voltage-gated sodium channels is essential for the propagation of itch sensation from the skin. Transmission of the itch impulses results in the unpleasant sensation that elicits the desire or reflex to scratch.

Multiple causes and electrical pathways for eliciting itch are known. In humans, pruritus can be elicited by histamine or PAR-2 agonists such as mucunain that activate distinct populations of C fibers (Namer, B., et al., J. Neurophysiol. (2008), 100: 2062-9). A variety of neurotrophic peptides are known to mediate itch in animal models (Wang, H., and Yosipovitch, G., International Journal of Dermatology (2010), 49: 1-11). Itch can also be elicited by opioids, evidence of distinct pharmacology from that of pain responses.

There exists a complex interaction between itch and pain responses that arises in part from the overlapping sensory input from the skin (Ikoma, A., et al., Arch. Dermatol. (2003), 139: 1475-8) and also from the diverse etiology of both pain and pruritus. Pain responses can exacerbate itching by enhancing central sensitization or lead to inhibition of painful scratching. Particularly severe forms of chronic itch occur when pain responses are absent, as in the case of post-herpetic itch (Oaklander, A. L., et al., Pain (2002), 96: 9-12).

The compounds of the invention can also be useful for treating pruritus. The rationale for treating itch with inhibitors of voltage-gated sodium channels, especially NaV1.7, is as follows:

The propagation of electrical activity in the C fibers that sense pruritinergic stimulants requires sodium entry through voltage-gated sodium channels.

NaV1.7 is expressed in the C fibers and kerotinocytes in human skin (Zhao, P., et al., Pain (2008), 139: 90-105).

A gain of function mutation of NaV1.7 (L858F) that causes erythromelalgia also causes chronic itch (Li, Y., et al., Clinical and Experimental Dermatology (2009), 34: e313-e4).

Chronic itch can be alleviated with treatment by sodium channel blockers, such as the local anesthetic lidocaine (Oaklander, A. L., et al., Pain (2002), 96: 9-12; Villamil, A. G., et al., The American Journal of Medicine (2005), 118: 1160-3). In these reports, lidocaine was effective when administered either intravenously or topically (a Lidoderm patch). Lidocaine can have multiple activities at the plasma concentrations achieved when administered systemically, but when administered topically, the plasma concentrations are only about 1 μM (Center for Drug Evaluation and Research NDA 20-612). At these concentrations, lidocaine is selective for sodium channel block and inhibits spontaneous electrical activity in C fibers and pain responses in animal models (Xiao, W. H., and Bennett, G. J. Pain (2008), 137: 218-28). The types of itch or skin irritation, include, but are not limited to:

psoriatic pruritus, itch due to hemodyalisis, aguagenic pruritus, and itching caused by skin disorders (e.g., contact dermatitis), systemic disorders, neuropathy, psychogenic factors or a mixture thereof;

itch caused by allergic reactions, insect bites, hypersensitivity (e.g., dry skin, acne, eczema, psoriasis), inflammatory conditions or injury;

itch associated with vulvar vestibulitis; and

skin irritation or inflammatory effect from administration of another therapeutic such as, for example, antibiotics, antivirals and antihistamines.

The compounds of the invention are also useful in treating certain cancers, such as hormone sensitive cancers, such as prostate cancer (adenocarcinoma), breast cancer, ovarian cancer, testicular cancer and thyroid neoplasia, in a mammal, preferably a human. The voltage gated sodium channels have been demonstrated to be expressed in prostate and breast cancer cells. Up-regulation of neonatal NaV1.5 occurs as an integral part of the metastatic process in human breast cancer and could serve both as a novel marker of the metastatic phenotype and a therapeutic target (Clin. Cancer Res. (2005), Aug. 1; 11(15): 5381-9). Functional expression of voltage-gated sodium channel alpha-subunits, specifically NaV1.7, is associated with strong metastatic potential in prostate cancer (CaP) in vitro. Voltage-gated sodium channel alpha-subunits immunostaining, using antibodies specific to the sodium channel alpha subunit was evident in prostatic tissues and markedly stronger in CaP vs non-CaP patients (Prostate Cancer Prostatic Dis., 2005; 8(3):266-73). See also Diss, J. K. J., et al., Mol. Cell. Neurosci. (2008), 37:537-547 and Kis-Toth, K., et al., The Journal of Immunology (2011), 187:1273-1280.

In consideration of the above, in one embodiment, the present invention provides a method for treating a mammal for, or protecting a mammal from developing, a sodium channel-mediated disease, especially pain, comprising administering to the mammal, especially a human, a therapeutically effective amount of a compound of the invention or a pharmaceutical composition comprising a therapeutically effective amount of a compound of the invention wherein the compound modulates the activity of one or more voltage-dependent sodium channels.

In another embodiment of the invention is a method of treating a disease or a condition in a mammal, preferably a human, wherein the disease or condition is selected from the group consisting of pain, depression, cardiovascular diseases, respiratory diseases, and psychiatric diseases, and combinations thereof, and wherein the method comprises administering to the mammal a therapeutically effective amount of an embodiment of a compound of the invention, as set forth above, as a stereoisomer, enantiomer or tautomer thereof or mixtures thereof, or a pharmaceutically acceptable salt, solvate or prodrug thereof, or a pharmaceutical composition comprising a therapeutically effective amount of a compound of the invention, as set forth above, as a stereoisomer, enantiomer or tautomer thereof or mixtures thereof, or a pharmaceutically acceptable salt, solvate or prodrug thereof, and a pharmaceutically acceptable excipient.

One embodiment of this embodiment is wherein the disease or condition is selected from the group consisting of acute pain, chronic pain, neuropathic pain, inflammatory pain, visceral pain, cancer pain, chemotherapy pain, trauma pain, surgical pain, post surgical pain, childbirth pain, labor pain, neurogenic bladder, ulcerative colitis, persistent pain, peripherally mediated pain, centrally mediated pain, chronic headache, migraine headache, sinus headache, tension headache, phantom limb pain, peripheral nerve injury, and combinations thereof.

Another embodiment of this embodiment is wherein the disease or condition is selected from the group consisting of pain associated with HIV, HIV treatment induced neuropathy, trigeminal neuralgia, post herpetic neuralgia, eudynia, heat sensitivity, tosarcoidosis, irritable bowel syndrome, Crohns disease, pain associated with multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), diabetic neuropathy, peripheral neuropathy, arthritic, rheumatoid arthritis, osteoarthritis, atherosclerosis, paroxysmal dystonia, myasthenia syndromes, myotonia, malignant hyperthermia, cystic fibrosis, pseudoaldosteronism, rhabdomyolysis, hypothyroidism, bipolar depression, anxiety, schizophrenia, sodium channel toxin related illnesses, familial erythromelalgia, primary erythromelalgia, familial rectal pain, cancer, epilepsy, partial and general tonic seizures, restless leg syndrome, arrhythmias, fibromyalgia, neuroprotection under ischaemic conditions caused by stroke or neural trauma, tachy arrhythmias, atrial fibrillation and ventricular fibrillation.

Another embodiment of the invention is a method of treating, but not preventing, pain in a mammal, wherein the method comprises administering to the mammal a therapeutically effective amount of a compound of the invention, as set forth above, as a stereoisomer, enantiomer or tautomer thereof or mixtures thereof, or a pharmaceutically acceptable salt, solvate or prodrug thereof, or a pharmaceutical composition comprising a therapeutically effective amount of a compound of the invention, as set forth above, as a stereoisomer, enantiomer or tautomer thereof or mixtures thereof, or a pharmaceutically acceptable salt, solvate or prodrug thereof, and a pharmaceutically acceptable excipient.

One embodiment of this embodiment is a method wherein the pain is selected from the group consisting of neuropathic pain, inflammatory pain, visceral pain, cancer pain, chemotherapy pain, trauma pain, surgical pain, post surgical pain, childbirth pain, labor pain, dental pain, chronic pain, persistent pain, peripherally mediated pain, centrally mediated pain, chronic headache, migraine headache, sinus headache, tension headache, phantom limb pain, peripheral nerve injury, trigeminal neuralgia, post herpetic neuralgia, eudynia, familial erythromelalgia, primary erythromelalgia, familial rectal pain or fibromyalgia, and combinations thereof.

Another embodiment of this embodiment is a method wherein the pain is associated with a disease or condition selected from HIV, HIV treatment induced neuropathy, heat sensitivity, tosarcoidosis, irritable bowel syndrome, Crohns disease, multiple sclerosis, amyotrophic lateral sclerosis, diabetic neuropathy, peripheral neuropathy, rheumatoid arthritis, osteoarthritis, atherosclerosis, paroxysmal dystonia, myasthenia syndromes, myotonia, malignant hyperthermia, cystic fibrosis, pseudoaldosteronism, rhabdomyolysis, hypothyroidism, bipolar depression, anxiety, schizophrenia, sodium channel toxin related illnesses, neurogenic bladder, ulcerative colitis, cancer, epilepsy, partial and general tonic seizures, restless leg syndrome, arrhythmias, ischaemic conditions caused by stroke or neural trauma, tachy arrhythmias, atrial fibrillation and ventricular fibrillation.

Another embodiment of the invention is the method of treating pain in a mammal, preferably a human, by the inhibition of ion flux through a voltage dependent sodium channel in the mammal, wherein the method comprises administering to the mammal a therapeutically effective amount of an embodiment of a compound of the invention, as set forth above, as a stereoisomer, enantiomer or tautomer thereof or mixtures thereof, or a pharmaceutically acceptable salt, solvate or prodrug thereof, or a pharmaceutical composition comprising a therapeutically effective amount of a compound of the invention, as set forth above, as a stereoisomer, enantiomer or tautomer thereof or mixtures thereof, or a pharmaceutically acceptable salt, solvate or prodrug thereof, and a pharmaceutically acceptable excipient.

Another embodiment of the invention is the method of treating pruritus in a mammal, preferably a human, wherein the method comprises administering to the mammal a therapeutically effective amount of an embodiment of a compound of the invention, as set forth above, as a stereoisomer, enantiomer or tautomer thereof or mixtures thereof, or a pharmaceutically acceptable salt, solvate or prodrug thereof, or a pharmaceutical composition comprising a therapeutically effective amount of a compound of the invention, as set forth above, as a stereoisomer, enantiomer or tautomer thereof or mixtures thereof, or a pharmaceutically acceptable salt, solvate or prodrug thereof, and a pharmaceutically acceptable excipient.

Another embodiment of the invention is the method of treating cancer in a mammal, preferably a human, wherein the method comprises administering to the mammal a therapeutically effective amount of an embodiment of a compound of the invention, as set forth above, as a stereoisomer, enantiomer or tautomer thereof or mixtures thereof, or a pharmaceutically acceptable salt, solvate or prodrug thereof, or a pharmaceutical composition comprising a therapeutically effective amount of a compound of the invention, as set forth above, as a stereoisomer, enantiomer or tautomer thereof or mixtures thereof, or a pharmaceutically acceptable salt, solvate or prodrug thereof, and a pharmaceutically acceptable excipient.

Another embodiment of the invention is the method of decreasing ion flux through a voltage dependent sodium channel in a cell in a mammal, wherein the method comprises contacting the cell with an embodiment of a compound of the invention, as set forth above, as a stereoisomer, enantiomer or tautomer thereof or mixtures thereof, or a pharmaceutically acceptable salt, solvate or prodrug thereof.

Another embodiment of the invention is the method of selectively inhibiting a first voltage-gated sodium channel over a second voltage-gated sodium channel in a mammal, wherein the method comprises administering to the mammal an inhibitory amount of a compound of formula (I), or an embodiment of a compound of formula (I).

Another embodiment of the invention is the method of selectively inhibiting NaV1.7 in a mammal or a mammalian cell as compared to NaV1.5, wherein the method comprises administering to the mammal an inhibitory amount of a compound of formula (I) or an embodiment of an embodiment thereof.

For each of the above embodiments described related to treating diseases and conditions in a mammal, the present invention also contemplates relatedly a compound of formula I or an embodiment thereof for the use as a medicament in the treatment of such diseases and conditions.

For each of the above embodiments described related to treating diseases and conditions in a mammal, the present invention also contemplates relatedly the use of a compound of formula I or an embodiment thereof for the manufacture of a medicament for the treatment of such diseases and conditions.

Another embodiment of the invention is a method of using the compounds of formula (I) as standards or controls in in vitro or in vivo assays in determining the efficacy of test compounds in modulating voltage-dependent sodium channels.

In another embodiment of the invention, the compounds of formula (I) are isotopically-labeled by having one or more atoms therein replaced by an atom having a different atomic mass or mass number.

Such isotopically-labeled (i.e., radiolabelled) compounds of formula (I) are considered to be within the scope of this invention. Examples of isotopes that can be incorporated into the compounds of formula (I) include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorous, sulfur, fluorine, chlorine, and iodine, such as, but not limited to, ²H, ³H, ¹¹C, ¹³C, ¹⁴C, ¹³N, ¹⁵N, ¹⁵O, ¹⁷O, ¹⁸O, ³¹P, ³²P, ³⁵S, ¹⁸F, ³⁶Cl, ¹²³I, and ¹²⁵I, respectively. These isotopically-labeled compounds would be useful to help determine or measure the effectiveness of the compounds, by characterizing, for example, the site or mode of action on the sodium channels, or binding affinity to pharmacologically important site of action on the sodium channels, particularly NaV1.7. Certain isotopically-labeled compounds of formula (I), for example, those incorporating a radioactive isotope, are useful in drug and/or substrate tissue distribution studies. The radioactive isotopes tritium, i.e. ³H, and carbon-14, i.e., ¹⁴C, are particularly useful for this purpose in view of their ease of incorporation and ready means of detection.

Substitution with heavier isotopes such as deuterium, i.e. ²H, may afford certain therapeutic advantages resulting from greater metabolic stability, for example, increased in vivo half-life or reduced dosage requirements, and hence may be preferred in some circumstances.

Substitution with positron emitting isotopes, such as ¹¹C, ¹⁸F, ¹⁵O and ¹³N, can be useful in Positron Emission Topography (PET) studies for examining substrate receptor occupancy. Isotopically-labeled compounds of formula (I) can generally be prepared by conventional techniques known to those skilled in the art or by processes analogous to those described in the Examples as set out below using an appropriate isotopically-labeled reagent in place of the non-labeled reagent previously employed.

Testing Compounds

The assessment of the compounds of the invention in mediating, especially inhibiting, the sodium channel ion flux can be determined using the assays described hereinbelow. Alternatively, the assessment of the compounds in treating conditions and diseases in humans may be established in industry standard animal models for demonstrating the efficacy of compounds in treating pain. Animal models of human neuropathic pain conditions have been developed that result in reproducible sensory deficits (allodynia, hyperalgesia, and spontaneous pain) over a sustained period of time that can be evaluated by sensory testing. By establishing the degree of mechanical, chemical, and temperature induced allodynia and hyperalgesia present, several physiopathological conditions observed in humans can be modeled allowing the evaluation of pharmacotherapies.

In rat models of peripheral nerve injury, ectopic activity in the injured nerve corresponds to the behavioural signs of pain. In these models, intravenous application of the sodium channel blocker and local anesthetic lidocaine can suppress the ectopic activity and reverse the tactile allodynia at concentrations that do not affect general behaviour and motor function (Mao, J. and Chen, L. L, Pain (2000), 87:7-17). Allometric scaling of the doses effective in these rat models, translates into doses similar to those shown to be efficacious in humans (Tanelian, D. L. and Brose, W. G., Anesthesiology (1991), 74(5):949-951). Furthermore, Lidoderm®, lidocaine applied in the form of a dermal patch, is currently an FDA approved treatment for post-herpetic neuralgia (Devers, A. and Glaler, B. S., Clin. J. Pain (2000), 16(3):205-8).

The present invention readily affords many different means for identification of sodium channel modulating agents that are useful as therapeutic agents. Identification of modulators of sodium channel can be assessed using a variety of in vitro and in vivo assays, e.g., measuring current, measuring membrane potential, measuring ion flux, (e.g., sodium or guanidinium), measuring sodium concentration, measuring second messengers and transcription levels, and using e.g., voltage-sensitive dyes, radioactive tracers, and patch-clamp electrophysiology.

One such protocol involves the screening of chemical agents for ability to modulate the activity of a sodium channel thereby identifying it as a modulating agent.

A typical assay described in Bean et al., J. General Physiology (1983), 83:613-642, and Leuwer, M., et al., Br. J. Pharmacol (2004), 141(1):47-54, uses patch-clamp techniques to study the behaviour of channels. Such techniques are known to those skilled in the art, and may be developed, using current technologies, into low or medium throughput assays for evaluating compounds for their ability to modulate sodium channel behaviour.

Throughput of test compounds is an important consideration in the choice of screening assay to be used. In some strategies, where hundreds of thousands of compounds are to be tested, it is not desirable to use low throughput means. In other cases, however, low throughput is satisfactory to identify important differences between a limited number of compounds. Often it will be necessary to combine assay types to identify specific sodium channel modulating compounds.

Electrophysiological assays using patch clamp techniques is accepted as a gold standard for detailed characterization of sodium channel compound interactions, and as described in Bean et al., op. cit. and Leuwer, M., et al., op. cit. There is a manual low-throughput screening (LTS) method which can compare 2-10 compounds per day; a recently developed system for automated medium-throughput screening (MTS) at 20-50 patches (i.e. compounds) per day; and a technology from Molecular Devices Corporation (Sunnyvale, Calif.) which permits automated high-throughput screening (HTS) at 1000-3000 patches (i.e. compounds) per day.

One automated patch-clamp system utilizes planar electrode technology to accelerate the rate of drug discovery. Planar electrodes are capable of achieving high-resistance, cells-attached seals followed by stable, low-noise whole-cell recordings that are comparable to conventional recordings. A suitable instrument is the PatchXpress 7000A (Axon Instruments Inc, Union City, Calif.). A variety of cell lines and culture techniques, which include adherent cells as well as cells growing spontaneously in suspension are ranked for seal success rate and stability. Immortalized cells (e.g. HEK and CHO) stably expressing high levels of the relevant sodium ion channel can be adapted into high-density suspension cultures.

Other assays can be selected which allow the investigator to identify compounds which block specific states of the channel, such as the open state, closed state or the resting state, or which block transition from open to closed, closed to resting or resting to open. Those skilled in the art are generally familiar with such assays.

Binding assays are also available. Designs include traditional radioactive filter based binding assays or the confocal based fluorescent system available from Evotec OAI group of companies (Hamburg, Germany), both of which are HTS.

Radioactive flux assays can also be used. In this assay, channels are stimulated to open with veratridine or aconitine and held in a stabilized open state with a toxin, and channel blockers are identified by their ability to prevent ion influx. The assay can use radioactive 22[Na] and 14[C] guanidinium ions as tracers. FlashPlate & Cytostar-T plates in living cells avoids separation steps and are suitable for HTS. Scintillation plate technology has also advanced this method to HTS suitability. Because of the functional aspects of the assay, the information content is reasonably good.

Yet another format measures the redistribution of membrane potential using the FLIPR system membrane potential kit (HTS) available from Molecular Dynamics (a division of Amersham Biosciences, Piscataway, N.J.). This method is limited to slow membrane potential changes. Some problems may result from the fluorescent background of compounds. Test compounds may also directly influence the fluidity of the cell membrane and lead to an increase in intracellular dye concentrations. Still, because of the functional aspects of the assay, the information content is reasonably good.

Sodium dyes can be used to measure the rate or amount of sodium ion influx through a channel. This type of assay provides a very high information content regarding potential channel blockers. The assay is functional and would measure Na+ influx directly. CoroNa Red, SBFI and/or sodium green (Molecular Probes, Inc. Eugene Oreg.) can be used to measure Na influx; all are Na responsive dyes. They can be used in combination with the FLIPR instrument. The use of these dyes in a screen has not been previously described in the literature. Calcium dyes may also have potential in this format.

In another assay, FRET based voltage sensors are used to measure the ability of a test compound to directly block Na influx. Commercially available HTS systems include the VIPR™ II FRET system (Life Technologies, or Aurora Biosciences Corporation, San Diego, Calif., a division of Vertex Pharmaceuticals, Inc.) which may be used in conjunction with FRET dyes, also available from Aurora Biosciences. This assay measures sub-second responses to voltage changes. There is no requirement for a modifier of channel function. The assay measures depolarization and hyperpolarizations, and provides ratiometric outputs for quantification. A somewhat less expensive MTS version of this assay employs the FLEXstation™ (Molecular Devices Corporation) in conjunction with FRET dyes from Aurora Biosciences. Other methods of testing the compounds disclosed herein are also readily known and available to those skilled in the art.

Modulating agents so identified are then tested in a variety of in vivo models so as to determine if they alleviate pain, especially chronic pain or other conditions such as cancer and pruritus (itch) with minimal adverse events. The assays described below in the Biological Assays Section are useful in assessing the biological activity of the instant compounds.

Typically, the efficacy of a compound of the invention is expressed by its IC50 value (“Inhibitory Concentration−50%”), which is the measure of the amount of compound required to achieve 50% inhibition of the activity of the target sodium channel over a specific time period. For example, representative compounds of the present invention have demonstrated IC50's ranging from less than 100 nanomolar to less than 10 micromolar in the patch voltage clamp NaV1.7 electrophysiology assay described herein.

In another aspect of the invention, the compounds of the invention can be used in in vitro or in vivo studies as exemplary agents for comparative purposes to find other compounds also useful in treatment of, or protection from, the various diseases disclosed herein.

Another aspect of the invention relates to inhibiting NaV1.1, NaV1.2, NaV1.3, NaV1.4, NaV1.5, NaV1.6, NaV1.7, NaV1.8, or NaV1.9 activity, preferably NaV1.7 activity, in a biological sample or a mammal, preferably a human, which method comprises administering to the mammal, preferably a human, or contacting said biological sample with a compound of formula (I) or a pharmaceutical composition comprising a compound of formula (I). The term “biological sample”, as used herein, includes, without limitation, cell cultures or extracts thereof; biopsied material obtained from a mammal or extracts thereof; and blood, saliva, urine, feces, semen, tears, or other body fluids or extracts thereof.

Inhibition of NaV1.1, NaV1.2, NaV1.3, NaV1.4, NaV1.5, NaV1.6, NaV1.7, NaV1.8, or NaV1.9 activity in a biological sample is useful for a variety of purposes that are known to one of skill in the art. Examples of such purposes include, but are not limited to, the study of sodium ion channels in biological and pathological phenomena; and the comparative evaluation of new sodium ion channel inhibitors.

The compounds of the invention (or stereoisomers, geometric isomers, tautomers, solvates, metabolites, isotopes, pharmaceutically acceptable salts, or prodrugs thereof) and/or the pharmaceutical compositions described herein which comprise a pharmaceutically acceptable excipient and one or more compounds of the invention, can be used in the preparation of a medicament for the treatment of sodium channel-mediated disease or condition in a mammal.

Combination Therapy

The compounds of the invention may be usefully combined with one or more other compounds of the invention or one or more other therapeutic agent or as any combination thereof, in the treatment of sodium channel-mediated diseases and conditions. For example, a compound of the invention may be administered simultaneously, sequentially or separately in combination with other therapeutic agents, including, but not limited to:

opiates analgesics, e.g., morphine, heroin, cocaine, oxymorphine, levorphanol, levallorphan, oxycodone, codeine, dihydrocodeine, propoxyphene, nalmefene, fentanyl, hydrocodone, hydromorphone, meripidine, methadone, nalorphine, naloxone, naltrexone, buprenorphine, butorphanol, nalbuphine and pentazocine;

non-opiate analgesics, e.g., acetaminophen, salicylates (e.g., aspirin);

nonsteroidal antiinflammatory drugs (NSAIDs), e.g., ibuprofen, naproxen, fenoprofen, ketoprofen, celecoxib, diclofenac, diflusinal, etodolac, fenbufen, fenoprofen, flufenisal, flurbiprofen, ibuprofen, indomethacin, ketoprofen, ketorolac, meclofenamic acid, mefenamic acid, meloxicam, nabumetone, naproxen, nimesulide, nitroflurbiprofen, olsalazine, oxaprozin, phenylbutazone, piroxicam, sulfasalazine, sulindac, tolmetin and zomepirac;

anticonvulsants, e.g., carbamazepine, oxcarbazepine, lamotrigine, valproate, topiramate, gabapentin and pregabalin;

antidepressants such as tricyclic antidepressants, e.g., amitriptyline, clomipramine, despramine, imipramine and nortriptyline;

COX-2 selective inhibitors, e.g., celecoxib, rofecoxib, parecoxib, valdecoxib, deracoxib, etoricoxib, and lumiracoxib;

alpha-adrenergics, e.g., doxazosin, tamsulosin, clonidine, guanfacine, dexmetatomidine, modafinil, and 4-amino-6,7-dimethoxy-2-(5-methane sulfonamido-1,2,3,4-tetrahydroisoquinol-2-yl)-5-(2-pyridyl) quinazoline;

barbiturate sedatives, e.g., amobarbital, aprobarbital, butabarbital, butabital, mephobarbital, metharbital, methohexital, pentobarbital, phenobartital, secobarbital, talbutal, theamylal and thiopental;

tachykinin (NK) antagonist, particularly an NK-3, NK-2 or NK-1 antagonist, e.g., (αR,9R)-7-[3,5-bis(trifluoromethyl)benzyl)]-8,9,10,11-tetrahydro-9-methyl-5-(4-methylphenyl)-7H-[1,4]diazocino[2,1-g][1,7]-naphthyridine-6-13-dione (TAK-637), 5-[[2R,3S)-2-[(1R)-1-[3,5-bis(trifluoromethylphenyl]ethoxy-3-(4-fluorophenyl)-4-morpholinyl]-methyl]-1,2-dihydro-3H-1,2,4-triazol-3-one (MK-869), aprepitant, lanepitant, dapitant or 3-[[2-methoxy5-(trifluoromethoxy)phenyl]-methylamino]-2-phenylpiperidine (2S,3S);

coal-tar analgesics, in particular paracetamol;

serotonin reuptake inhibitors, e.g., paroxetine, sertraline, norfluoxetine (fluoxetine desmethyl metabolite), metabolite demethylsertraline, ‘3 fluvoxamine, paroxetine, citalopram, citalopram metabolite desmethylcitalopram, escitalopram, d,l-fenfluramine, femoxetine, ifoxetine, cyanodothiepin, litoxetine, dapoxetine, nefazodone, cericlamine, trazodone and fluoxetine;

noradrenaline (norepinephrine) reuptake inhibitors, e.g., maprotiline, lofepramine, mirtazepine, oxaprotiline, fezolamine, tomoxetine, mianserin, buproprion, buproprion metabolite hydroxybuproprion, nomifensine and viloxazine (Vivalan®)), especially a selective noradrenaline reuptake inhibitor such as reboxetine, in particular (S,S)-reboxetine, and venlafaxine duloxetine neuroleptics sedative/anxiolytics;

dual serotonin-noradrenaline reuptake inhibitors, such as venlafaxine, venlafaxine metabolite O-desmethylvenlafaxine, clomipramine, clomipramine metabolite desmethylclomipramine, duloxetine, milnacipran and imipramine;

acetylcholinesterase inhibitors such as donepezil;

5-HT3 antagonists such as ondansetron;

metabotropic glutamate receptor (mGluR) antagonists;

local anaesthetic such as mexiletine and lidocaine;

corticosteroid such as dexamethasone;

antiarrhythimics, e.g., mexiletine and phenytoin;

muscarinic antagonists, e.g., tolterodine, propiverine, tropsium t chloride, darifenacin, solifenacin, temiverine and ipratropium;

cannabinoids;

vanilloid receptor agonists (e.g., resinferatoxin) or antagonists (e.g., capsazepine);

sedatives, e.g., glutethimide, meprobamate, methaqualone, and dichloralphenazone;

anxiolytics such as benzodiazepines,

antidepressants such as mirtazapine,

topical agents (e.g., lidocaine, capsacin and resiniferotoxin);

muscle relaxants such as benzodiazepines, baclofen, carisoprodol, chlorzoxazone, cyclobenzaprine, methocarbamol and orphrenadine;

anti-histamines or H1 antagonists;

NMDA receptor antagonists;

5-HT receptor agonists/antagonists;

PDEV inhibitors;

Tramadol®;

cholinergic (nicotinc) analgesics;

alpha-2-delta ligands;

prostaglandin E2 subtype antagonists;

leukotriene B4 antagonists;

5-lipoxygenase inhibitors; and

5-HT3 antagonists.

Sodium channel-mediated diseases and conditions that may be treated and/or prevented using such combinations include but not limited to, pain, central and peripherally mediated, acute, chronic, neuropathic as well as other diseases with associated pain and other central nervous disorders such as epilepsy, anxiety, depression and bipolar disease; or cardiovascular disorders such as arrhythmias, atrial fibrillation and ventricular fibrillation; neuromuscular disorders such as restless leg syndrome and muscle paralysis or tetanus; neuroprotection against stroke, neural trauma and multiple sclerosis; and channelopathies such as erythromyalgia and familial rectal pain syndrome.

As used herein “combination” refers to any mixture or permutation of one or more compounds of the invention and one or more other compounds of the invention or one or more additional therapeutic agent. Unless the context makes clear otherwise, “combination” may include simultaneous or sequentially delivery of a compound of the invention with one or more therapeutic agents. Unless the context makes clear otherwise, “combination” may include dosage forms of a compound of the invention with another therapeutic agent. Unless the context makes clear otherwise, “combination” may include routes of administration of a compound of the invention with another therapeutic agent. Unless the context makes clear otherwise, “combination” may include formulations of a compound of the invention with another therapeutic agent. Dosage forms, routes of administration and pharmaceutical compositions include, but are not limited to, those described herein.

The invention will be more fully understood by reference to the following examples. They should not, however, be construed as limiting the scope of the invention.

EXAMPLES

These examples serve to provide guidance to a skilled artisan to prepare and use the compounds, compositions and methods of the invention. While particular embodiments of the present invention are described, the skilled artisan will appreciate that various changes and modifications can be made without departing from the spirit and scope of the inventions.

The chemical reactions in the examples described can be readily adapted to prepare a number of other compounds of the invention, and alternative methods for preparing the compounds of this invention are deemed to be within the scope of this invention. For example, the synthesis of non-exemplified compounds according to the invention can be successfully performed by modifications apparent to those skilled in the art, for example, by appropriately protecting interfering group, by utilizing other suitable reagents known in the art, for example, by appropriately protecting interfering groups by utilizing other suitable reagents known in the art other than those described, and/or by making routine modifications of reaction conditions.

In the examples below, unless otherwise indicated all temperatures are set forth in degrees Celcius. Commerically available reagents were purchased from suppliers such as Aldrich Chemical Company, Lancaster, TCI or Maybridge and were used without further purification unless otherwise indicated. The reactions set forth below were done generally under a positive pressure of nitrogen or argon or with a drying tube (unless otherwise stated) in anhydrous solvents, and the reaction flasks were typically fitted with rubber septa for the introduction of substrates and reagents via syringe. Glassware was oven dried and/or heat dried. ¹H NMR spectra were obtained in deuterated CDCl₃, d₆-DMSO, CH₃OD or d₆-acetone solvent solutions (reported in ppm) using or trimethylsilane (TMS) or residual non-deuterated solvent peaks as the reference standard. When peak multiplicities are reported, the following abbreviates are used: s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet, br (broadened), dd (doublet of doublets), dt (doublet of triplets). Coupling constants, when given, ar reported in Hz (Hertz).

All abbreviations used to describe reagents, reaction conditions or equipment are intended to be consistent with the definitions set forth in the “List of standard abbreviates and acronyms”. The chemical names of discrete compounds of the invention were obtained using the structure naming feature of ChemDraw naming program.

LCMS Analytical Methods

Final compounds were analyzed using three different LC/MS conditions, with UV detector monitoring at 214 nm and 254 nm, and mass spectrometry scanning 110-800 amu in ESI+ ionization mode.

LC/MS Method A: (8.0 min LC-MS Run): XBridge C18 column (4.6×50 mm, 3.5 μm, 40° C.); mobile phase: A=10 mM ammonium hydrogen carbonate in water, B=acetonitrile; gradient: 0.0-8.0 min, 5%-95% B; flow rate=1.2 mL/min.

LC/MS Method B: (8.0 min LC-MS Run): XBridge C18 column (4.6×50 mm, 3.5 μm, 40° C.); mobile phase: A=0.1% ammonia in water, B=acetonitrile; gradient: 0.0-8.0 min, 5%-95% B; flow rate=1.2 mL/min.

LC/MS Method C: (8.0 min LC-MS Run): XBridge C18 column (4.6×50 mm, 3.5 μm, 40° C.); mobile phase: A=0.1% TFA in water, B=acetonitrile; gradient: 0.0-8.0 min, 5%-95% B; flow rate=1.2 mL/min.

LC/MS Method D: Agilent SB C18, 2.1×30 mm, 1.8 μm; mobile phase: A water (0.05% TFA), B CH₃CN (0.05% TFA); gradient: 3% B (0.3 min), followed by 3-95% B (6.5 min), 95% B (1.5 min); flow rate: 0.4 mL/min; oven temperature 25° C.

LC/MS Method E: Acquity BEH C18, 2.1×50 mm, 1.8 μm; mobile phase: A water (0.1% FA), B CH₃CN (0.1% FA); gradient: 3% B (0.4 min), followed by 3-95% B (7.5 min), 95% B (0.5 min); flow rate: 0.5 mL/min; oven temperature 25° C.

Abbreviations

MeCN Acetonitrile

EtOAc Ethyl acetate

DCE Dichloroethane

DCM Dichloromethane

DIPEA Diisopropylethylamine

DEA Diethylamine

DMAP 4-dimethylaminopyridine

DMF N,N-Dimethylformamide

DMSO Dimethyl sulfoxide

FA Formic acid

IPA Isopropyl alcohol

TFA Trifluoroacetic acid

EDCI 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride

HCl Hydrochloric acid

HPLC High Pressure Liquid Chromatography

LCMS Liquid Chromatography Mass Spectrometry

MeOH Methanol

NMP N-methyl-2-pyrrolidone

RPHPLC Reverse phase high pressure liquid chromatography

RT Retention time

SFC Supercritical Fluid Chromatography

THF Tetrahydrofuran

TEA Triethylamine

Example 1

(S)-6-fluoro-4-((2S,4R)-2-(pyridin-2-yl)-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide

Step 1 (R,Z)-2-methyl-N-(1-(pyridin-2-yl)ethylidene)propane-2-sulfinamide

To a mixture of (R)-2-methylpropane-2-sulfinamide (105 g, 0.86 mol) and 1-(pyridin-2-yl)ethanone (95 g, 0.78 mol) in DCM (1.5 L) was slowly added titanium(IV) ethoxide (322 mL, 1.57 mol) under a nitrogen atmosphere. The reaction mixture was heated to 40° C. for 16 h. After cooling to room temperature, sat. aq. NaHCO₃ (350 mL) was added and filtered through a short pad of anhydrous Na₂SO₄, washed with DCM (3 L). The organic layer was concentrated in vacuo. The crude residue was purified by silica gel chromatography (petroleum ether/EtOAc=5:1) to give the title compound (85 g, 48%) as a yellow solid. ¹H NMR (400 MHz, CDCl₃) δ 8.66 (d, J=4.4 Hz, 1H), 8.14 (d, J=8.0 Hz, 1H), 7.81-7.73 (m, 1H), 7.43-7.33 (m, 1H), 2.88 (s, 3H), 1.34 (s, 9H).

Step 2 (S,Z)-ethyl 5-(((R)-tert-butylsulfinyl)imino)-5-(pyridin-2-yl)-3-(trifluoromethyl)pentanoate

To a solution of (R,Z)-2-methyl-N-(1-(pyridin-2-yl)ethylidene)propane-2-sulfinamide (85 g, 0.38 mol) in anhydrous THF (850 mL) at −78° C. was added lithium diisopropylamide (2.0 M, 199 mL, 0.40 mmol). The reaction mixture was stirred at −78° C. for 2 h, ethyl 4,4,4-trifluorobut-2-enoate (67 g, 0.40 mol) in anhydrous THF (100 mL) was added. The reaction mixture was warmed up to 0° C. over 30 min period and stirred at 0° C. for 3 h. The reaction was quenched with sat. aq. ammonium chloride (500 mL), extracted with EtOAc (1 L×2), washed with brine (500 mL), dried over anhydrous Na₂SO₄, filtered and concentrated in vacuo. The crude residue was purified by silica gel chromatography (petroleum ether/EtOAc=5:1) to give the title compound (47 g, 32%) as yellow oil. ¹H NMR (400 MHz, CDCl₃) δ 8.67 (d, J=4.8 Hz, 1H), 8.00 (s, 1H), 7.81-7.74 (m, 1H), 7.43-7.35 (m, 1H), 4.09-3.92 (m, 3H), 3.64-3.46 (m, 2H), 2.68 (d, J=6.0 Hz, 2H), 1.36 (s, 9H), 1.17 (t, J=7.2 Hz, 3H).

Step 3 (S)-ethyl 5-oxo-5-(pyridin-2-yl)-3-(trifluoromethyl)pentanoate

To a solution of (S,Z)-ethyl 5-(((R)-tert-butylsulfinyl)imino)-5-(pyridin-2-yl)-3-(trifluoromethyl)pentanoate (47 g, 0.12 mol) in EtOH (400 mL) was added aq. HCl (4.0 M, 150 mL, 0.60 mol). The reaction mixture was stirred at 40° C. for 3 h. After cooling to room temperature, EtOAc (1 L) was added, washed with sat. aq. Na₂CO₃ (500 mL×2), brine (500 mL), dried over anhydrous Na₂SO₄, filtered and concentrated in vacuo. The crude residue was purified by silica gel chromatography (petroleum ether/EtOAc=10:1) to give the title compound (31 g, 89%) as yellow oil. LCMS M/Z (M+H) 290.

Step 4 (3R)-1-(pyridin-2-yl)-3-(trifluoromethyl)pentane-1,5-diol

To a solution of lithium aluminium hydride (10 g, 0.27 mol) in anhydrous THF (450 mL) at 0° C. was added (S)-ethyl 5-oxo-5-(pyridin-2-yl)-3-(trifluoromethyl)pentanoate (26.3 g, 90.9 mmol) in anhydrous THF (50 mL) dropwise under a nitrogen atmosphere. The reaction mixture was stirred at 0° C. for 1 h. The reaction was quenched with water (11 mL) and 15% aq. NaOH (11 mL), dried over anhydrous MgSO₄, filtered. The filtrate was concentrated in vacuo to give the title compound (13 g, 57%) as light yellow oil that required no further purification. LCMS M/Z (M+H) 250.

Step 5 (R)-5-oxo-5-(pyridin-2-yl)-3-(trifluoromethyl)pentanal

To a mixture of (3R)-1-(2-pyridyl)-3-(trifluoromethyl)pentane-1,5-diol (12.0 g, 48.15 mmol) in N,N-dimethylformamide (240 mL) at 0° C. was added Dess-Martin periodinane (42.89 g, 101.11 mmol). The mixture was stirred at room temperature for 16 h. The mixture was diluted with EtOAc (3 L), washed with sat. aq. Na₂CO₃ (1 L×2) and water (1 L×2), dried over anhydrous Na₂SO₄, filtered and concentrated in vacuo. The residue was purified by silica gel chromatography (petroleum ether/EtOAc=5:1) to give the title compound (3R)-5-oxo-5-(2-pyridyl)-3-(trifluoromethyl)pentanal (7.8 g, 66%) as yellow oil. ¹H NMR (400 MHz, CDCl₃) δ 9.79 (s, 1H), 8.69 (d, J=4.4 Hz, 1H), 8.09-8.02 (m, 1H), 7.91-7.83 (m, 1H), 7.55-7.49 (m, 1H), 3.73-3.59 (m, 2H), 3.49-3.38 (m, 1H), 2.88-2.79 (m, 1H), 2.69-2.60 (m, 1H)

Step 6 (S)-N-(2,4-dimethoxybenzyl)-6-fluoro-4-((2S,4R)-2-(pyridin-2-yl)-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide

To a solution of (3R)-5-oxo-5-(2-pyridyl)-3-(trifluoromethyl)pentanal (992 mg, 4.05 mmol) and (S)-4-amino-N-(2,4-dimethoxybenzyl)-N-(1,2,4-thiadiazol-5-yl)chroman-7-sulfonamide (1.2 g, 2.53 mmol) in toluene (40 mL) was added titanium(IV) isopropoxide (1.87 mL, 6.32 mmol) under a nitrogen atmosphere. The reaction mixture was stirred at room temperature for 3 h. Sodium triacetoxyborohydride (8.04 g, 37.93 mmol) was added to the mixture and stirred at room temperature for an additional 16 h. EtOAc (100 mL) was added and washed with water (50 mL×2), brine (50 mL). The organic layer was dried over anhydrous MgSO₄, filtered and concentrated in vacuo. The crude residue was purified by silica gel chromatography (DCM/EtOAc=2:1) to give the title compound (1.5 g, 54%) as a white solid. LCMS M/Z (M+H) 688.

Step 7 (S)-6-fluoro-4-((2S,4R)-2-(pyridin-2-yl)-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide

A mixture of (S)-N-(2,4-dimethoxybenzyl)-6-fluoro-4-((2S,4R)-2-(pyridin-2-yl)-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide (1.5 g, 1.35 mmol) and formic acid (15 mL) was stirred at room temperature for 1 h. The mixture was concentrated in vacuo. The residue was purified by reverse phase chromatography (acetonitrile 55-75%/0.225% formic acid in water) to give the title compound (427 mg, 59%) as a white solid. ¹H NMR (400 MHz, DMSO-d₆) δ 8.57 (s, 1H), 8.51 (d, J=4.8 Hz, 1H), 8.25-8.24 (m, 1H), 7.82-7.76 (m, 1H), 7.66 (d, J=8.0 Hz, 1H), 7.56 (d, J=10.8 Hz, 1H), 7.32-7.26 (m, 1H), 7.14 (d, J=6.0 Hz, 1H), 7.00 (d, J=4.0 Hz, 1H), 4.28-4.21 (m, 1H), 3.90-3.78 (m, 2H), 3.56-3.52 (m, 1H), 2.58-2.54 (m, 2H), 2.44-2.32 (m, 1H), 2.07-1.94 (m, 1H), 1.91-1.70 (m, 4H), 1.53-1.51 (m, 1H). LCMS M/Z (M+H) 538.

Example 2

(S)-6-fluoro-4-((2S,4S)-2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide

Step 1

benzyl 2-(4-fluorophenyl)-4-oxo-3,4-dihydropyridine-1 (2H)-carboxylate

To a solution of 4-methoxypyridine (10.0 g, 91.63 mmol) in anhydrous THF (250 mL) at −20° C. was slowly added benzyl carbonochloridate (17.01 mL, 119 mmol) under a nitrogen atmosphere. The reaction mixture was stirred at room temperature for 1 h. (4-fluorophenyl)magnesium bromide in THF (1.0 M, 146.61 mL, 146.61 mmol) at −20° C. was added to the mixture and stirred at the same temperature for an additional 1 h. The mixture was quenched with 3% aq. hydrogen chloride (40 mL) and extracted with toluene (40 mL). The organic layer was washed with 4.5% aq. NaHCO₃ (40 mL), dried over anhydrous Na₂SO₄, filtered and concentrated in vacuo. Isopropyl alcohol (15 mL) was added to the mixture and stirred at room temperature for 1 h. The solid was isolated by filtered. The filter cake was washed with isopropyl alcohol (5 mL×3) and dried in vacuo to give the title compound (14 g, 47%) as a white solid. ¹H NMR (400 MHz, DMSO-d₆) δ 8.06 (d, J=8.4 Hz, 1H), 7.42-7.30 (m, 5H), 7.27-7.22 (m, 2H), 7.20-7.12 (m, 2H), 5.74 (d, J=7.2 Hz, 1H), 5.36-5.17 (m, 3H), 3.32-3.20 (m, 1H), 2.62 (d, J=16.8 Hz, 1H). LCMS M/Z (M+H) 326.

Step 2

benzyl 2-(4-fluorophenyl)-4-oxopiperidine-1-carboxylate

A mixture of benzyl 2-(4-fluorophenyl)-4-oxo-3,4-dihydropyridine-1(2H)-carboxylate (14.0 g, 43.03 mmol) and zinc powder (28.14 g, 430.33 mmol) in acetic acid (100 mL) was stirred at room temperature for 24 h. The mixture was filtered and the filter cake was washed with acetic acid (30 mL×3). The filtrate was concentrated in vacuo. The crude residue was purified by silica gel chromatography (petroleum ether/EtOAc=3:1) to give the title compound (14 g, 99%) as colorless oil. LCMS M/Z (M+H) 328.

Step 3

(trans)-benzyl 2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidine-1-carboxylate & (cis)-benzyl 2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidine-1-carboxylate

To a solution of benzyl 2-(4-fluorophenyl)-4-oxopiperidine-1-carboxylate (12.0 g, 36.66 mmol) in anhydrous THF (200 mL) at 0° C. was added (trifluoromethyl)trimethylsilane (19.06 mL, 47.66 mmol) and tetrabutylammonium fluoride in THF (1.0 M, 3.67 mL, 3.67 mmol). The reaction mixture was stirred at room temperature for 16 h. Water (50 mL) was added and extracted with EtOAc (50 mL). The organic layer was dried over anhydrous Na₂SO₄, filtered and concentrated in vacuo. The crude residue was purified by silica gel chromatography (petroleum ether/EtOAc=10:1) to give (trans)-benzyl 2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidine-1-carboxylate rac-5B (3.4 g, less polar on TLC) as a white solid and (cis)-benzyl 2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidine-1-carboxylate rac-5A (0.88 g, more polar on TLC) as a white solid. Trans-isomer: ¹H NMR (400 MHz, CDCl₃) δ 7.31-7.25 (m, 3H), 7.22-7.16 (m, 2H), 7.11-7.05 (m, 2H), 7.03-6.96 (m, 2H), 5.15-4.97 (m, 3H), 4.33-4.25 (m, 1H), 3.42-3.28 (m, 1H), 2.55 (s, 1H), 2.27-2.12 (m, 2H), 2.06-1.99 (m, 1H), 1.97-1.86 (m, 1H). LCMS M/Z (M+H) 398. Cis-isomer: ¹H NMR (400 MHz, CDCl₃) δ 7.30-7.24 (m, 3H), 7.22-7.15 (m, 2H), 7.11-7.05 (m, 2H), 7.03-6.95 (m, 2H), 5.15-4.97 (m, 3H), 4.35-4.22 (m, 1H), 3.41-3.29 (m, 1H), 2.57 (s, 1H), 2.28-2.12 (m, 2H), 2.08-1.98 (m, 1H), 1.97-1.84 (m, 1H). LCMS M/Z (M+H) 398.

Step 4

(2S,4S)-benzyl 2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidine-1-carboxylate & (2R,4R)-benzyl 2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidine-1-carboxylate

(cis)-Benzyl 2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidine-1-carboxylate (0.88 g) was separated by using chiral SFC (Whelk-01 250 mm*30 mm, 10 UM, Supercritical CO₂/MeOH+DEA=70/30; 70 ml/min) to give (2S,4S)-benzyl 2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidine-1-carboxylate (0.37 g, first peak) as a white solid and (2R,4R)-benzyl 2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidine-1-carboxylate (0.38 g, second peak) as a white solid.

Step 5

(2S,4S)-2-(4-fluorophenyl)-4-(trifluoromethyl)piperidin-4-ol

To solution of benzyl (2S,4S)-2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidine-1-carboxylate (1.2 g, 3.02 mmol) in EtOH (20 mL) was added 20% palladium hydroxide on carbon (1.09 g). The mixture was stirred at room temperature for 1 h under a hydrogen atmosphere (15 psi). The mixture was filtered and the filtrate was concentrated in vacuo to give the title compound (700 mg, crude) as a white solid that required no further purification. ¹H NMR (400 MHz, CDCl₃) δ 7.37-7.35 (m, 2H), 7.04-7.00 (m, 2H), 4.02-3.98 (m, 1H), 3.19-3.12 (m, 2H), 1.90-1.65 (m, 4H).

Step 6 (R)-7-(N-(2,4-dimethoxybenzyl)-N-(pyrimidin-4-yl)sulfamoyl)-6-fluorochroman-4-yl methanesulfonate

To a solution of (R)—N-(2,4-dimethoxybenzyl)-6-fluoro-4-hydroxy-N-(pyrimidin-4-yl)chroman-7-sulfonamide (800 mg, 1.68 mmol) and triethylamine (0.7 mL, 5.05 mmol) in DCM (10 mL) at 0° C. was added methanesulfonic anhydride (586 mg, 3.36 mmol) in DCM (3 mL). The resulting mixture was stirred at room temperature for 2 h. The mixture was diluted with DCM (30 mL), washed with 10% aqueous citric acid (20 mL), sat. aq. NaHCO₃ (20 mL), brine (10 mL), dried over anhydrous Na₂SO₄, filtered and concentrated in vacuo to give the title compound (750 mg, crude) as a yellow solid that required no further purification. ¹H NMR (400 MHz, CDCl₃) δ 8.80 (s, 1H), 8.47 (d, J=6.0 Hz, 1H), 7.54 (d, J=6.0 Hz, 1H), 7.27-7.18 (m, 3H), 6.43-6.41 (m, 2H), 5.75-5.73 (m, 1H), 5.27 (s, 2H), 4.42-4.38 (m, 1H), 4.31-4.25 (m, 1H), 3.79 (s, 3H), 3.78 (s, 3H), 3.10 (s, 3H), 2.40-2.36 (m, 1H), 2.35-2.18 (m, 1H).

Step 7

(S)-N-(2,4-dimethoxybenzyl)-6-fluoro-4-((2S,4S)-2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide & (R)—N-(2,4-dimethoxybenzyl)-6-fluoro-4-((2S,4S)-2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide

To a solution of (2S,4S)-2-(4-fluorophenyl)-4-(trifluoromethyl)piperidin-4-ol (190 mg, 0.72 mmol) and (R)-7-(N-(2,4-dimethoxybenzyl)-N-(pyrimidin-4-yl)sulfamoyl)-6-fluorochroman-4-yl methanesulfonate (799 mg, 1.44 mmol) in EtOAc (4 mL) was added N,N-diisopropylethylamine (0.6 mL, 3.61 mmol). The mixture was heated to 80° C. for 16 h under a nitrogen atmosphere. After cooling to room temperature, the mixture was concentrated in vacuo. The residue was purified by silica gel chromatography (petroleum ether/EtOAc=5:1) to give (R)—N-(2,4-dimethoxybenzyl)-6-fluoro-4-((2S,4S)-2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide (70 mg, 13.5%, less polar on TLC) and (S)-N-(2,4-dimethoxybenzyl)-6-fluoro-4-((2S,4S)-2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide (170 mg, 33%, more polar on TLC) as colorless oil. LCMS M/Z (M+H) 721.

Step 8

(S)-6-fluoro-4-((2S,4S)-2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide

A mixture of (S)-N-(2,4-dimethoxybenzyl)-6-fluoro-4-((2S,4S)-2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide (300 mg, 0.42 mmol) and formic acid (5 mL) was stirred at room temperature for 1 h. The mixture was concentrated in vacuo. The residue was purified by reverse phase chromatography (acetonitrile 40-70%/0.225% formic acid in water) to give the title compound (50 mg, 21%) as a white solid. ¹H NMR (400 MHz, DMSO-d₆) 8.56 (s, 1H), 8.25 (d, J=2.0 Hz, 1H), 7.59-7.49 (m, 3H), 7.18-7.13 (m, 3H), 6.99 (s, 1H), 6.03 (s, 1H), 4.27-4.24 (m, 1H), 3.96-3.93 (m, 1H), 3.82-3.79 (m, 1H), 3.67-3.63 (m, 1H), 2.68-2.63 (m, 1H), 2.36-2.33 (m, 1H), 2.03-1.94 (m, 1H), 1.86-1.76 (m, 4H), 1.68-1.65 (m, 1H). LCMS M/Z (M+H) 571.

Example 3

(S)-4-((2S,4R)-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidin-1-yl)-6-fluoro-N-(pyrimidin-4-yl)chroman-7-sulfonamide

Step 1

(trans)-benzyl 4-(difluoromethoxy)-2-(4-fluorophenyl)piperidine-1-carboxylate & (cis)-benzyl 4-(difluoromethoxy)-2-(4-fluorophenyl)piperidine-1-carboxylate

To a solution of benzyl 2-(4-fluorophenyl)-4-hydroxy-piperidine-1-carboxylate (20.0 g, 60.72 mmol) in acetonitrile (200 mL) was added CuI (2.32 g, 12.16 mmol). The mixture was heated to 45° C. Then 2,2-difluoro-2-(fluorosulfonyl)acetic acid (21.64 g, 121.44 mmol) was added dropwise for 0.5 h. The mixture was heated to 45° C. for an additional 2 h. After cooling to room temperature, the mixture was concentrated in vacuo. EtOAc (200 mL) was added, washed with brine (100 mL), dried over anhydrous Na₂SO₄, filtered and concentrated in vacuo. The residue was purified by silica gel chromatography (petroleum ether/EtOAc=5:1) to give (trans)-benzyl-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidine-1-carboxylate (4.3 g, 19%, less polar on TLC) and (cis) benzyl-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidine-1-carboxylate (6 g, crude, more polar on TLC) as colorless oil. The cis-product (6 g, crude) was re-purified by reverse phase chromatography (acetonitrile 55-85%/0.225% formic acid in water) to give (cis)-benzyl-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidine-1-carboxylate (3 g, 13%) as colorless oil. Trans-isomer: ¹H NMR (400 MHz, CDCl₃) δ 7.44-7.28 (m, 5H), 7.23-7.16 (m, 2H), 7.09-7.01 (m, 2H), 6.45-6.03 (m, 1H), 5.67 (s, 1H), 5.71-5.62 (m, 1H), 5.71-5.62 (m, 1H), 5.22 (s, 2H), 4.40-4.18 (m, 2H), 2.89-2.76 (m, 1H), 2.73-2.61 (m, 1H), 2.04-1.92 (m, 2H), 1.75-1.62 (m, 1H). LCMS M/Z (M+H) 380. Cis-isomer: ¹H NMR (400 MHz, CDCl₃) δ 7.37-7.24 (m, 5H), 7.21-7.14 (m, 2H), 7.03-6.95 (m, 2H), 6.19-5.79 (m, 1H), 5.45-5.35 (m, 1H), 5.20-5.12 (m, 2H), 4.66-4.59 (m, 1H), 4.19-4.08 (m, 1H), 3.37-3.25 (m, 1H), 2.57-2.47 (m, 1H), 2.22-2.13 (m, 1H), 1.97-1.78 (m, 2H). LCMS M/Z (M+H) 380.

Step 2

(2R,4S)-benzyl 4-(difluoromethoxy)-2-(4-fluorophenyl)piperidine-1-carboxylate & (2S,4R)-benzyl 4-(difluoromethoxy)-2-(4-fluorophenyl)piperidine-1-carboxylate

(Cis)-benzyl-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidine-1-carboxylate (3.0 g, 7.91 mmol) was separated by chiral SFC (Chiralpak OJ (250 mm*50 mm, 10 um), Supercritical CO₂/IPA+0.1% NH₄OH=85/15; 180 mL/min) to give (2R,4S)-benzyl 4-(difluoromethoxy)-2-(4-fluorophenyl)piperidine-1-carboxylate (1.2 g, 40%, first peak) and (2S,4R)-benzyl 4-(difluoromethoxy)-2-(4-fluorophenyl)piperidine-1-carboxylate (1.3 g, 43%, second peak) as yellow oil. LCMS M/Z (M+H) 380.

Step 3

(2S,4R)-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidine

To a solution of (2S,4R)-benzyl 4-(difluoromethoxy)-2-(4-fluorophenyl)piperidine-1-carboxylate (1.3 g, 3.43 mmol) in MeOH (20 mL) was added 20% palladium hydroxide on carbon (500 mg). The mixture was stirred at room temperature for 1 h under a hydrogen atmosphere (15 psi). The mixture was filtered and the filtrate was concentrated in vacuo to give the title compound (800 mg, 95%) as a white solid. LCMS M/Z (M+H) 246

Step 4

(S)-4-((2S,4R)-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidin-1-yl)-N-(2,4-dimethoxybenzyl)-6-fluoro-N-(pyrimidin-4-yl)chroman-7-sulfonamide & (R)-4-((2S,4R)-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidin-1-yl)-N-(2,4-dimethoxybenzyl)-6-fluoro-N-(pyrimidin-4-yl)chroman-7-sulfonamide

To a solution of (2S,4R)-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidine (300 mg, 1.23 mmol) and N,N-diisopropylethylamine (1.01 mL, 6.12 mmol) in ethyl acetate (12 mL) was added (R)-7-(N-(2,4-dimethoxybenzyl)-N-(pyrimidin-4-yl)sulfamoyl)-6-fluorochroman-4-yl methanesulfonate (1.31 g, 2.45 mmol). The mixture was heated to 80° C. for 16 h under a nitrogen atmosphere. After cooling to room temperature, the mixture was concentrated in vacuo. The residue was purified by prep-TLC (50% EtOAc in petroleum ether) to give (S)-4-((2S,4R)-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidin-1-yl)-N-(2,4-dimethoxybenzyl)-6-fluoro-N-(pyrimidin-4-yl)chroman-7-sulfonamide (155 mg, 18%, more polar on TLC) and (R)-4-((2S,4R)-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidin-1-yl)-N-(2,4-dimethoxybenzyl)-6-fluoro-N-(pyrimidin-4-yl)chroman-7-sulfonamide (160 mg, 19%, less polar on TLC) as white solid. LCMS M/Z (M+H) 703.

Step 5

(S)-4-((2S,4R)-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidin-1-yl)-6-fluoro-N-(pyrimidin-4-yl)chroman-7-sulfonamide

A mixture of (S)-4-((2S,4R)-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidin-1-yl)-N-(2,4-dimethoxybenzyl)-6-fluoro-N-(pyrimidin-4-yl)chroman-7-sulfonamide (155 mg, 0.22 mmol) and formic acid (3 mL) was stirred at room temperature for 1 h. The mixture was concentrated in vacuo. The residue was purified by reverse phase chromatography (acetonitrile 30-60%/0.225% formic acid in water) to give the title compound (75 mg, 62%) as a white solid. ¹H NMR (400 MHz, DMSO-d₆) δ 8.57 (s, 1H), 8.31-8.20 (m, 1H), 7.52-7.42 (m, 2H), 7.19 (d, J=10.4 Hz, 1H), 7.15-7.06 (m, 3H), 7.03-6.95 (m, 1H), 6.89-6.48 (m, 1H), 4.22-4.08 (m, 3H), 3.90-3.75 (m, 2H), 2.72-2.67 (m, 1H), 2.28-2.17 (m, 1H), 2.02-1.90 (m, 3H), 1.83-1.73 (m, 1H), 1.68-1.54 (m, 2H). LCMS M/Z (M+H) 553.

Example 4

(S)-6-fluoro-4-((2R,4R)-2-methyl-4-(3-(trifluoromethyl)phenyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide

Step 1

(2S,3R)-tert-butyl 2-acetyl-5-oxo-3-(3-(trifluoromethyl)phenyl)pentanoate

A mixture of (E)-3-(3-(trifluoromethyl)phenyl)acrylaldehyde (1.27 g, 6.32 mmol) in water (12 mL) was added (S)-2-(bis(3,5-bis(trifluoromethyl)phenyl)((trimethylsilyl)oxy)methyl)pyrrolidine (378 mg, 0.63 mmol) and tert-butyl 3-oxobutanoate (1.0 g, 6.32 mmol). The reaction mixture was stirred at room temperature for 16 h. The mixture was diluted with EtOAc (100 mL), washed with water (50 mL) and brine (50 mL), dried over anhydrous Na₂SO₄, filtered and concentrated in vacuo to give the title compound (2.25 g, crude) as a yellow oil. ¹H NMR (400 MHz, CDCl₃) δ 9.64-9.59 (m, 1H), 7.56-7.38 (m, 4H), 4.10-4.01 (m, 1H), 3.87-3.84 (m, 1H), 2.96-2.76 (m, 2H), 2.06-2.04 (m, 3H), 1.16-1.12 (m, 9H).

Step 2

(R)-5-oxo-3-(3-(trifluoromethyl)phenyl)hexanal

A solution of (2S,3R)-tert-butyl 2-acetyl-5-oxo-3-(3-(trifluoromethyl)phenyl)pentanoate (1.0 g, 2.79 mmol) in 2,2,2-trifluoroacetic acid (5 mL) and dichloromethane (5 mL) was stirred at room temperature for 1 h. The reaction was quenched with NaHCO₃ (50 mL), extracted with EtOAc (50 mL). The organic layer was dried over anhydrous Na₂SO₄, filtered and concentrated in vacuo to give the title compound (720 mg, crude) as yellow oil.

Step 3

(S)-N-(2,4-dimethoxybenzyl)-6-fluoro-4-((2R,4R)-2-methyl-4-(3-(trifluoromethyl)phenyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide

To a solution of (R)-5-oxo-3-(3-(trifluoromethyl)phenyl)hexanal (327 mg, 1.26 mmol) and (S)-4-amino-N-(2,4-dimethoxybenzyl)-N-(1,2,4-thiadiazol-5-yl)chroman-7-sulfonamide (400 mg, 0.84 mmol) in toluene (10 mL) was added titanium(IV) isopropoxide (0.62 mL, 2.1 mmol) under a nitrogen atmosphere. The reaction mixture was stirred at room temperature for 3 h. Sodium triacetoxyborohydride (1.79 g, 8.42 mmol) was added to the mixture and stirred at room temperature for an additional 16 h. EtOAc (100 mL) was added and washed with water (50 mL×2), brine (50 mL). The organic layer was dried over anhydrous MgSO₄, filtered and concentrated in vacuo. The crude residue was purified by reverse phase chromatography (acetonitrile 75-100%/0.05% ammonia hydroxide in water) to give the title compound (50 mg, 8%) as a white solid. ¹H NMR (400 MHz, CDCl₃) δ 8.78 (s, 1H), 8.44 (d, J=5.6 Hz, 1H), 7.52-7.44 (m, 3H), 7.43-7.39 (m, 3H), 7.30 (d, J=5.2 Hz, 1H), 7.23 (d, J=8.0 Hz, 1H), 6.45-6.39 (m, 2H), 5.31 (s, 2H), 4.52-4.45 (m, 1H), 4.19-4.04 (m, 2H), 3.81 (s, 3H), 3.78 (s, 3H), 2.95-2.87 (m, 1H), 2.78-2.58 (m, 3H), 2.30-2.18 (m, 1H), 2.15-2.07 (m, 1H), 1.94-1.74 (m, 3H), 1.53-1.41 (m, 1H), 0.74 (s, 3H). LCMS M/Z (M+H) 701.

Step 4

(S)-6-fluoro-4-((2R,4R)-2-methyl-4-(3-(trifluoromethyl)phenyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide

A mixture of (S)-N-(2,4-dimethoxybenzyl)-6-fluoro-4-((2R,4R)-2-methyl-4-(3-(trifluoromethyl)phenyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide (50 mg, 0.07 mmol) and formic acid (1 mL) was stirred at room temperature for 1 h. The mixture was concentrated in vacuo. The residue was purified by reverse phase chromatography (acetonitrile 26-56%/0.225% formic acid in water) to give the title compound (26 mg, 67%) as a white solid. ¹H NMR (400 MHz, DMSO-d₆) δ 8.54 (s, 1H), 8.25 (d, J=6.0 Hz, 1H), 7.61-7.51 (m, 4H), 7.49-7.40 (m, 1H), 7.17 (d, J=6.0 Hz, 1H), 6.98 (d, J=6.4 Hz, 1H), 4.46-4.38 (m, 1H), 4.24-4.08 (m, 2H), 2.94-2.83 (m, 1H), 2.78-2.64 (m, 3H), 2.15-2.01 (m, 2H), 1.85-1.67 (m, 3H), 1.49-1.36 (m, 1H), 0.71 (s, 3H). LCMS M/Z (M+H) 551.

Example 5: Tritiated Compound Binding to Membranes Isolated from Cells that Heterologously Express hNav1.7 and the β1 Subunit

Preparation of membranes containing recombinantly expressed sodium channels: Frozen recombinant cell pellets were thawed on ice and diluted to 4 times the cell pellet weight with ice cold 50 mM Tris HCl, pH 7.4 buffer. The cell suspensions were homogenized on ice using a motorized glass dounce homogeniser. Homogenates were further diluted 8.4 times with ice cold 50 mM Tris HCl, pH 7.4 buffer and then centrifuged at 200×g at 4° C. for 15 min. The supernatants were collected and centrifuged at 10000×g at 4° C. for 50 min. The pellets were then re-suspended in 100 mM NaCl, 20 mM Tris HCl, pH 7.4 buffer containing 1% v/v protease inhibitors (Calbiochem) and re-homogenized on ice. The homogenized membranes were then processed through a syringe equipped with a 26 gauge needle. Protein concentrations were determined by Bradford Assay and the membranes were stored at −80° C.

Radioligand Binding Studies:

Saturation experiments. A competitive NaV1.7 inhibitor having a methyl group was tritiated. Three tritiums were incorporated in place of methyl hydrogens to generate [³H]compound. Binding of this radioligand was performed in 5 mL borosilicate glass test tubes at room temperature. Binding was initiated by adding membranes to increasing concentrations of [³H]compound in 100 mM NaCl, 20 mM Tris HCl, pH 7.4 buffer containing 0.01% w/v bovine serum albumin (BSA) for 18h. Non-specific binding was determined in the presence of 1 μM unlabeled compound. After 18h, the reactants were filtered through GF/C glass fiber filters presoaked in 0.5% w/v polyethylene imine. Filters were washed with 15 mL ice cold 100 mM NaCl, 20 mM Tris HCl, pH7.4 buffer containing 0.25% BSA to separate bound from free ligand. [³H]compound bound to filters was quantified by liquid scintillation counting.

Competitive Binding Experiments:

Binding reactions were performed in 96-well polypropylene plates at room temperature for 18h. In 360 μL, membranes were incubated with 100 pM [³H]compound and increasing concentrations of Test Compound. Non-specific binding was defined in the presence of 1 μM unlabeled compound. Reactions were transferred and filtered through 96-well glass fiber/C filter plates presoaked with 0.5% polyethylene imine. The filtered reactions were washed 5 times with 200 μL ice cold buffer containing 0.25% BSA. Bound radioactivity was determined by liquid scintillation counting.

Data Analysis: For saturation experiments, non-specific binding was subtracted from total binding to provide specific binding and these values were recalculated in terms of pmol ligand bound per mg protein. Saturation curves were constructed and dissociation constants were calculated using the single site ligand binding model: Beq=(Bmax*X)/(X+Kd), where Beq is the amount of ligand bound at equilibrium, Bmax is the maximum receptor density, Kd is the dissociation constant for the ligand, and X is the free ligand concentration. For competition studies percent inhibition was determined and IC50 values were calculated using a 4 parameter logistic model (% inhibition=(A+((B−A)/(1+((x/C){circumflex over ( )}D)))) using XLfit, where A and B are the maximal and minimum inhibition respectively, C is the IC50 concentration and D is the (Hill) slope.

Representative compounds, when tested in this model or another representative model of inhibition, demonstrated in vitro Nav1.7 inhibition as set forth in Table 1 below.

Example 6: In Vivo Pharmacokinetic Experiments (Compound Clearance in Rats)

In vivo clearance (CL_(p)) of certain compounds was measured in order to evaluate whether these compounds were likely to be good candidates for development. Male rats were housed at controlled temperature and humidity in an alternating 12 hr light/dark cycle with access to food and water ad libitum. All in vivo studies were performed in accordance with Institutional Animal Care and Use Committee guidelines and in harmony with the Guide for Laboratory Animal Care and Use. Rats were administered IV administration of compound. Plasma was harvested from blood samples that were collected from each animal at various timepoints following the administration of compound. Plasma concentration of compound was determined by mass spectrometer, and pharmacokinetic analysis was performed using non-compartmental method using Phoenix WinNonlin. Following oral administration, percent bioavailability was determined for each animal by dividing the dose-normalized area under the plasma concentration-time curve from time 0 to the last measured concentration (AUC0-tlast) obtained following each oral dose by the mean dose-normalized AUC0-tlast of the animals dosed by IV injection.

Representative compounds, when tested in this model, demonstrated the pharmacokinetic (“PK”) property (CL_(p)) as set forth in Table 1 below. A compound demonstrating a CL_(p) value of about 40 mL/min/kg or less in the model of Example 6 is considered to be low to moderately cleared from the body, meaning that there may be reasonable exposure of a compound to a subject to be treated for a disease or disorder as provided herein. CL_(p) values above about 40 mL/min/kg in Example 6 are considered to be highly cleared from the body after administration of a compound to a subject, meaning that the exposure may be insufficient to be treated for a disease or disorder as provided herein. Each of the compounds of Table 1 demonstrated good stability as evidenced by CL_(p) values less than 30 mL/min/kg.

TABLE 1 Na_(v)1.7 inhib. in vitro PK (CL_(p), rat) Example Structure (μM) (mL/min/kg) 1

0.0005 <30 2

0.0005 <30 3

0.0022 <30 4

0.0034 <30

Table 2 shows additional representative compounds identified as potent Nav1.7 inhibitors, but which surprisingly demonstrated poor pharmacokinetic properties (i.e., CL_(p)) in the method described in Example 6 above.

TABLE 2 Na_(v)1.7 inhib. Reference in vitro PK (CL_(p), rat) Compound Structure (μM) (mL/min/kg) A

0.0011 >60 B

<0.0005   >60 C

0.0008 >60 D

0.011  >60 E

0.0026 >60 F

0.0088 >60

All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non patent publications referred to in this specification are incorporated herein by reference in their entireties.

Although the foregoing invention has been described in some detail to facilitate understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. Accordingly, the described embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims. 

We claim:
 1. A compound selected from the group consisting of: (S)-6-fluoro-4-((2S,4R)-2-(pyridin-2-yl)-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide; (S)-6-fluoro-4-((2S,4S)-2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide; (S)-4-((2S,4R)-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidin-1-yl)-6-fluoro-N-(pyrimidin-4-yl)chroman-7-sulfonamide; and (S)-6-fluoro-4-((2R,4R)-2-methyl-4-(3-(trifluoromethyl)phenyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide; or a pharmaceutically acceptable thereof.
 2. A compound of claim 1 which is: (S)-6-fluoro-4-((2S,4R)-2-(pyridin-2-yl)-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide, or a pharmaceutically acceptable salt thereof.
 3. A compound of claim 1 which is: (S)-6-fluoro-4-((2S,4S)-2-(4-fluorophenyl)-4-hydroxy-4-(trifluoromethyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide, or a pharmaceutically acceptable salt thereof.
 4. A compound of claim 1 which is: (S)-4-((2S,4R)-4-(difluoromethoxy)-2-(4-fluorophenyl)piperidin-1-yl)-6-fluoro-N-(pyrimidin-4-yl)chroman-7-sulfonamide, or a pharmaceutically acceptable salt thereof.
 5. A compound of claim 1 which is: (S)-6-fluoro-4-((2R,4R)-2-methyl-4-(3-(trifluoromethyl)phenyl)piperidin-1-yl)-N-(pyrimidin-4-yl)chroman-7-sulfonamide, or a pharmaceutically acceptable salt thereof.
 6. A pharmaceutical composition comprising a compound of claim 1, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient.
 7. A pharmaceutical composition comprising the compound of claim 2, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient.
 8. A pharmaceutical composition comprising the compound of claim 3, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient.
 9. A pharmaceutical composition comprising the compound of claim 4, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient.
 10. A pharmaceutical composition comprising the compound of claim 5, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient. 